History UsefulNotes / PrehistoricLifeOtherExtinctCreatures

'''The "First Tree" and the "First Shoot":''' ''[[http://en.wikipedia.org/wiki/Archaeopteris Archaeopteris]]'' & ''[[http://en.wikipedia.org/wiki/Cooksonia Cooksonia]]''

* Sometimes it seems paleontologists have fun making cryptic jokes with scientific names. While the traditional "first bird" is called ''[[UsefulNotes/StockDinosaursTrueDinosaurs Archaeopteryx]]'', one of the first land plants to ever appear is the almost-homonymous ''Archaeopteris''. But wait, ''Archaeopteryx'' means "ancient wing", ''Archaeopteris'' means "ancient fern". This plant lived in the Devonian (before the Carboniferous), just when the proto-amphibian ''Ichthyostega'' made the first step on dry land; it was one of the first terrestrial plants to develop to the size of a tree. Since at the time land animals were very few and mostly carnivorous or detritivorous, ''Archaeopteris'' and its relatives were able to spread worldwide, but never far from water, just like amphibians. Their appearence was like that of a tree fern: indeed, the fern's shape is considered one of the most primitive body plans among terrestrial plants. However, plants went on land ''before'' the amphibians. In the Silurian period (before the Devonian) there were already some aquatic plants (ex. the Psilophytes) emerging out of water; ''Cooksonia'' is an often-cited example. These tiny plants still kept their roots underwater, but their "branches" grew above the water's surface, capturing extra light. Terrestrial plants are actually very evolved organisms and have worked hard to develop adaptations for surviving outside the liquid element - among them, a vascular system (that is, tiny vessels for the flow of fluids), waterproof "skin", and fibers to make their stalks more robust against gravity.

'''The "First Tree":''' ''[[http://en.wikipedia.org/wiki/Archaeopteris Archaeopteris]]''

* Sometimes it seems paleontologists have fun making cryptic jokes with scientific names. While the traditional "first bird" is called ''[[UsefulNotes/StockDinosaursTrueDinosaurs Archaeopteryx]]'', one of the first land plants to ever appear is the almost-homonymous ''Archaeopteris''. But wait, ''Archaeopteryx'' means "ancient wing", ''Archaeopteris'' means "ancient fern". This plant lived in the Devonian (before the Carboniferous), just when the proto-amphibian ''Ichthyostega'' made the first step on dry land; it was one of the first terrestrial plants to develop to the size of a tree. Since at the time land animals were very few and mostly carnivorous or detritivorous, ''Archaeopteris'' and its relatives were able to spread worldwide, but never far from water, just like amphibians. Their appearence was like that of a tree fern: indeed, the fern's shape is considered one of the most primitive body plans among terrestrial plants.

'''The "First Shoot":''' ''[[http://en.wikipedia.org/wiki/Cooksonia Cooksonia]]''

* However, plants went on land ''before'' the amphibians. In the Silurian period (before the Devonian) there were already some aquatic plants (ex. the Psilophytes) emerging out of water; ''Cooksonia'' is an often-cited example. These tiny plants still kept their roots underwater, but their "branches" grew above the water's surface, capturing extra light. Terrestrial plants are actually very evolved organisms and have worked hard to develop adaptations for surviving outside the liquid element - among them, a vascular system (that is, tiny vessels for the flow of fluids), waterproof "skin", and fibers to make their stalks more robust against gravity.

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[[folder:Cephalopods]]

No other animal group has had a greater importance in paleontology than molluscs. Their fossils are extremely abundant, to the point that many rocky formations are composed mostly of fossilized mollusc shells. Among molluscs cephalopods deserve a mention apart, being much more "evolved" than the others. Together with arthropods, cephalopods are the extinct invertebrates you're most likely to see in media - at least, documentary media; you'll [[SmallTaxonomyPools rarely see]] a trilobite, ammonite, sea scorpion or nautiloid in Fictionland. If it happens, they'll be simple "ambient critters", and good luck if the animal [[NoNameGiven is mentioned]].

[[/folder]]

[[folder:Other Invertebrates]]

There isn't much to say about the portrayal of extinct non-arthropod/non-cephalopod invertebrates in media: they [[SeldomSeenSpecies rarely appear]] even in books and documentaries, much less in Fictionland, and when they do, they are almost [[NoNameGiven never named]] (except sometimes for the names of each group, but only in popular science works). As an example, the original Disney's ''WesternAnimation/{{Fantasia}}'' showed several ''modern'' critters to symbolize the early evolution of invertebrates, but [[SmallTaxonomyPools few or no]] ''truly'' prehistoric ones. The ''Walking With'' series did the same: only modern jellyfish, sponges and sea urchins appear, all live-action. Indeed, many modern invertebrate groups have populated our seas since the Cambrian Period, but many others are extinct today. Among modern land arthropods expect to see dragonflies, scorpions, centipedes, spiders, cockroaches, beetles, and sometimes crickets. They will be oversized: [[BigCreepyCrawlies roaches the size of a rat, scorpions as big as cats]], and so on. Finally, let's not forget a staple in every Paleozoic or Mesozoic sea: a jellyfish, used as the symbol of the most ancient forms of life.

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'''Clams and pseudo-Clams:''' [[http://en.wikipedia.org/wiki/Rudist Rudists]] and prehistoric ''[[http://en.wikipedia.org/wiki/Lingula Lingula]]''

* Gastropods, scaphopods, bivalves, brachiopods, chitons, monoplacophorans: [[RiddleMeThis who's the intruder?]] All these invertebrate groups were "shellfish", and all but one were molluscs: the exception is the brachiopods. They were only distant mollusc relatives, and more closely related to the coral-like bryozoans (see "sessile invertebrates" below). As a whole, molluscs and brachiopods are extremely abundant in fossil records of all ages, from the early Paleozoic up to the modern era. However, while molluscs are still a dominant group in modern seas, brachiopods are nearly extinct today, and thus cited as "living fossils". The most representative is probably ''Lingula'' ("small tongue"), a clam-like, filter-feeding animal that lives anchored to the sea floor with a fleshy protrusion (the "tongue"); prehistoric ''Lingula'' have been identical to modern ones since the Early Ordovician! Among extinct non-cephalopod molluscs worthy of note are the Rudists like ''Hippurites''. Exclusively Cretaceous, these clams are notable both for their often great size (some were as tall as a human), and for their unique shape. They can be described as giant cups with a lid: the lower valve (the one attached to the sea bed) was conical and much bigger than the flat upper valve. Like ''Lingula'', rudists were probably almost motionless creatures that filter-fed on tiny organisms.

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"Fish" is a catch-all word containing all non-tetrapod vertebrates; that is, all backboned animals which are ''not only'' fully-aquatic, but descend from fully-aquatic ancestors as well. Ichthyosaurs, plesiosaurs, mosasaurs and dolphins aren't fish, just because they ''did'' descend from land-living creatures (except they are... in the same way birds are dinosaurs, but in this case even humans are fish!). There are only two groups of fish which are still successful today: sharks and ray-finned fish. Not so in Prehistory, as you'll understand soon.

In paleontology, the word "amphibian" has traditionally had a much broader meaning than how it's commonly used. Amphibians were all [[http://en.wikipedia.org/wiki/Tetrapoda tetrapods]] (four-limbed vertebrates) excluding amniotes (reptiles + mammals). Today, even scientists tend to restrict the word to indicate only modern frogs, salamanders, caecilians, and their common ancestors. If you want to use "amphibians" in its former, broader sense, you have to call modern groups "lissamphibians". We'll use here amphibian in the old, wider meaning because it's much handier to say this rather than "basal tetrapod" every time we refer to non-frog, non-salamander, and non-caecilian animals.

Lissamphibians excluded, prehistoric amphibians are traditionally called "labyrinthodonts" ("labyrinth tooth") or "stegocephalians" ("roof-head"), but these terms shouldn't be used today, just like "thecodonts" for basal archosaurs or "pelycosaurs" for basal synapsids. They don't indicate any natural grouping of animals, but are instead catch-all words with little scientific significance [[ScienceMarchesOn in modern phylogenetic systematics]]. ''Labyrinthodont'' means "labyrinth teeth", because many of these animals had convoluted, labyrinth-like internal structures in their teeth, but this isn't a fundamental thing. Their importance was much, much greater than this and tied to a different aspect of their evolutionary history. They were, simply put, the links between fish and truly terrestrial vertebrates, a keystone group for mankind's evolution. And yet, just like synapsids and Mesozoic mammals, they have not gotten much attention in pop culture. If they appear at all in fictional works, they'll be simply described as "giant amphibians".

[[https://en.wikipedia.org/wiki/RNA_world The RNA world]] is about as far as we can look back. The RNA world is a well-founded hypothesis - it has enough evidence to be generally believed, but insufficient to be considered proven. In the modern world, DNA codes genes. Genes are copied to messenger RNA. Messenger RNA is read by ribosomes to create proteins. Almost all the functions of the cell are performed by proteins, including duplicating DNA and copying DNA to RNA, and most of the ribosome is protein. This works great, but how could it have started? DNA can't replicate without proteins, and proteins can't be made without the instructions in DNA. However, RNA can both store information ''and'' catalyze reactions. Although it would be grossly inefficient by modern standards, life based on RNA with no DNA and no proteins is quite plausible. The RNA world hypothesis is that such RNA life existed, and is ancestral to modern life. Evidence for this is functional RNA (RNA which does stuff directly, rather than simply being instructions to ribosomes), which performs just a few cellular functions, but very critical ones. Most central is that RNA forms the reactive core of the ribosomes.

** [[https://en.wikipedia.org/wiki/RNA_world The RNA world]] is about as far as we can look back. The RNA world is a well-founded hypothesis - it has enough evidence to be generally believed, but insufficient to be considered proven. In the modern world, DNA codes genes. Genes are copied to messenger RNA. Messenger RNA is read by ribosomes to create proteins. Almost all the functions of the cell are performed by proteins, including duplicating DNA and copying DNA to RNA, and most of the ribosome is protein. This works great, but how could it have started? DNA can't replicate without proteins, and proteins can't be made without the instructions in DNA. However, RNA can both store information ''and'' catalyze reactions. Although it would be grossly inefficient by modern standards, life based on RNA with no DNA and no proteins is quite plausible. The RNA world hypothesis is that such RNA life existed, and is ancestral to modern life. Evidence for this is functional RNA (RNA which does stuff directly, rather than simply being instructions to ribosomes), which performs just a few cellular functions, but very critical ones. Most central is that RNA forms the reactive core of the ribosomes.

'''Stony Arrows?:''' Extinct Octopuses and Squid

However, modern scientists do not accept such an unfairly "racistic" distinction. Furthermore, "lower animals" often show biological traits and behaviours traditionally considered typical of mammals and birds: social attitudes, parental care, intelligence, even some "warm-blood" abilities. Yet in popular media they may be treated as stupid/unfeeling brutes even to this day. Documentaries not excluded: within the ''[[Series/WalkingWithDinosaurs Walking With]]'' series, for example, ''Series/WalkingWithDinosaurs'' and ''Series/WalkingWithBeasts'' show dinosaurs and mammals as smart/social/caring creatures, while the meaningfully-named ''[[Series/WalkingWithMonsters Walking With]] [[PrehistoricMonster Monsters]]'' and ''[[SeaMonster Sea Monsters]]'' focus mainly on non-dino reptiles and all the animal groups listed below, with only animals vertebrates shown as being smart/social/caring (ArtisticLicenseBiology).

'''Stony Arrows?:''' Belemnites and extinct Octopuses and Squid

* Extinct cephalopods have given fuel to many legends, even before paleontology itself was "invented" by [[http:/en.wikipedia.org/wiki/Georges_Cuvier Georges Cuvier]] at the end of the 18th century. Before that, those strange things today called fossils were believed to be Nature's jokes, the Earth's flowers, or other things (only Creator/LeonardoDaVinci correctly recognized their nature, but his discovery was long ignored). And then there are more specific legends about cephalopod fossils. [[UsefulNotes/StockDinosaursNonDinosaurs Ammonites]] were believed to be stony horns ("ammonite" comes from Amun, an Ancient Egyptian deity who was often portrayed with rams' horns), or petrified snakes.[[note]]Some had fun sculpting snake heads on the shells' extremities to make them look like snakes![[/note]] The lesser-known belemnites (technically belemnoids), with their straight pointed shape, were believed to be stony arrows, or even the Devil's fingers! Belemnites were cephalopods living in the Mesozoic era together with ammonites, and probably gave rise to squid. Like ammonites, only their shells are usually preserved. This shell was ''inside'' the animal's body and invisible in life; belemnites would resemble simple squid or cuttlefish if alive today. Their lifestyle was more active than ammonites, and they were probably able to do the same things modern squid do (spraying ink, swimming using the lateral "fins", catching prey with their suckers, seeing images with their eyes). True modern squid became widespread in the Cretaceous, and the first octopuses (''[[http://en.wikipedia.org/wiki/Proteroctopus Proteroctopus]]'' for example) were already around in the Middle Jurassic; these molluscs (called "coleoids") usually have no shell inside, or at least only a remnant of shell (ex. the famous cuttle-bone). Some Cretaceous squid were as large as a modern giant or colossal squid.

* Temnospondyls survived the huge Permian mass extinction and made their way in the Triassic: only competition with crocodilians at the end of the period caused their decline and near-total extinction before the Jurassic. The most famous Triassic amphibian is the massive ''[[UsefulNotes/StockDinosaursNonDinosaurs Mastodonsaurus]]''; also very large but much more slender was ''Trematosaurus'', more similar to a gharial in shape. ''[[http://en.wikipedia.org/wiki/Aphaneramma Aphaneramma]]'' looked like the latter, but not as big. It was a rare example of a ''marine'' amphibian, with no parallels in the modern world, where all amphibians are freshwater or terrestrial creatures. ''Gerrothorax'' ("wicker chest") was much smaller than the mastodonsaur, and a bit similar to the unrelated arrow-headed ''Diplocaulus''. Interestingly, it shows neoteny: that is, adults retained the external gills of their larval stage, like the modern [[http://en.wikipedia.org/wiki/Axolotl axolotl]]). Another known neotenic paleoamphibian was the salamander-like ''[[http://en.wikipedia.org/wiki/Branchiosaurus Branchiosaurus]]'' ("gill lizard" - nothing to do with the dinosaur ''[[UsefulNotes/StockDinosaursTrueDinosaurs Brachiosaurus]]'', "arm lizard"). Few temnospondyls reached the Late Triassic: among them, the North American ''Metoposaurus'' had eyes located more frontally on its head than its earlier relatives, and was able to see ''[[UsefulNotes/StockDinosaursTrueDinosaurs Coelophysis]]'' in RealLife. In 1997 a new temnospondyl was unexpectedly discovered in Cretaceous terrain: ''Koolasuchus'' ("Koola's croc") was probably an isolated Australian late survivor which managed to resist the competition with freshwater reptiles. It shows up both in Series/WalkingWithDinosaurs and in Disney's ''Disney/{{Dinosaur}}'' (though rather inaccurately in the latter).

There isn't much to say about the portrayal of extinct non-arthropod/non-cephalopod invertebrates in media: they [[SeldomSeenSpecies rarely appear]] even in books and documentaries, much less in Fictionland, and when they do, they are almost [[NoNameGiven never named]] (except sometimes for the names of each group, but only in popular science works). As an example, the original Disney's ''Disney/{{Fantasia}}'' showed several ''modern'' critters to symbolize the early evolution of invertebrates, but [[SmallTaxonomyPools few or no]] ''truly'' prehistoric ones. The ''Walking With'' series did the same: only modern jellyfish, sponges and sea urchins appear, all live-action. Indeed, many modern invertebrate groups have populated our seas since the Cambrian Period, but many others are extinct today. Among modern land arthropods expect to see dragonflies, scorpions, centipedes, spiders, cockroaches, beetles, and sometimes crickets. They will be oversized: [[BigCreepyCrawlies roaches the size of a rat, scorpions as big as cats]], and so on. Finally, let's not forget a staple in every Paleozoic or Mesozoic sea: a jellyfish, used as the symbol of the most ancient forms of life.

[[folder:The origin of Life]]

'''Malagasy giant frog:''' ''[[https://en.wikipedia.org/wiki/Beelzebufo Beelzebufo]]''

'''Fish with limblike fins:''' ''[[http://en.wikipedia.org/wiki/Coelacanthus Coelacanthus]]'', ''[[http://en.wikipedia.org/wiki/Macropoma Macropoma]]'', ''[[http://en.wikipedia.org/wiki/Mawsonia Mawsonia]]'', ''[[http://en.wikipedia.org/wiki/Dipterus Dipterus]]'', and ''[[http://en.wikipedia.org/wiki/Ceratodus Ceratodus]]''

'''Fish that crawled onto land:''' ''[[http://en.wikipedia.org/wiki/Osteolepis Osteolepis]]'', ''[[http://en.wikipedia.org/wiki/Holoptychius Holoptychius]]'', ''[[http://en.wikipedia.org/wiki/Panderichthys Panderichthys]]'', ''[[http://en.wikipedia.org/wiki/Tiktaalik Tiktaalik]]'', and ''[[http://en.wikipedia.org/wiki/Acanthostega Acanthostega]]''

'''The most common fish group today:''' ''[[http://en.wikipedia.org/wiki/Leedsichthys Leedsichthys]]'', ''[[http://en.wikipedia.org/wiki/Lepidotes Lepidotes]]'', ''[[http://en.wikipedia.org/wiki/Leptolepis Leptolepis]]'', ''[[http://en.wikipedia.org/wiki/Enchodus Enchodus]]'', and ''[[http://en.wikipedia.org/wiki/Knightia Knightia]]''

'''The first fish with fishbones:''' ''[[http://en.wikipedia.org/wiki/Palaeoniscum Palaeoniscum]]'', ''[[http://en.wikipedia.org/wiki/Cheirolepis Cheirolepis]]'', ''[[http://en.wikipedia.org/wiki/Acanthodes Acanthodes]]'', and ''[[http://en.wikipedia.org/wiki/Climatius Climatius]]''

'''Tough guys:''' ''[[http://en.wikipedia.org/wiki/Bothriolepis Bothriolepis]]'', ''[[http://en.wikipedia.org/wiki/Pterichthyodes Pterichthyodes]]'', ''[[http://en.wikipedia.org/wiki/Coccosteus Coccosteus]]'', ''[[http://en.wikipedia.org/wiki/Lunaspis Lunaspis]]'', and the other Placoderms

'''The Aspis family:''' ''[[http://en.wikipedia.org/wiki/Hemicyclaspis Hemicyclaspis]]'', ''[[http://en.wikipedia.org/wiki/Arandaspis Arandaspis]]'', ''[[http://en.wikipedia.org/wiki/Astraspis Astraspis]]'', ''[[http://en.wikipedia.org/wiki/Drepanaspis Drepanaspis]]'', and the other "Ostracoderms"

'''Our earliest origins:''' ''[[http://en.wikipedia.org/wiki/Haikouichthys Haikouichthys]]'', ''[[http://en.wikipedia.org/wiki/Yunnanozoon Yunnanozoon]]'', ''[[http://en.wikipedia.org/wiki/Myllokunmingia Myllokunmingia]]'', and the [[http://en.wikipedia.org/wiki/Conodont conodonts]]

'''Out of water, at last!''' ''[[http://en.wikipedia.org/wiki/Palaeophonus Palaeophonus]]'', ''[[http://en.wikipedia.org/wiki/Arthrolycosa Arthrolycosa]]'', ''[[http://en.wikipedia.org/wiki/Euphoberia Euphoberia]]'', ''[[http://en.wikipedia.org/wiki/Rhyniella Rhyniella]]'', and other non-insect land arthropods

'''Stony Arrows?:''' Belemnites and extinct octopuses and squid

'''Finding Nemo:''' ''[[http://en.wikipedia.org/wiki/Orthoceras Orthoceras]]'' and the other "nautiloids"

'''Clams and pseudo-clams:''' [[http://en.wikipedia.org/wiki/Rudist Rudists]] and prehistoric ''[[http://en.wikipedia.org/wiki/Lingula Lingula]]''

'''Geometrical guys:''' [[http://en.wikipedia.org/wiki/Cystoid Cystoids]], [[http://en.wikipedia.org/wiki/Blastoid blastoids]], and [[http://en.wikipedia.org/wiki/Crinoid prehistoric crinoids]]

'''Our relatives?:''' [[http://en.wikipedia.org/wiki/Graptolite Graptolites]] and [[http://en.wikipedia.org/wiki/Homalozoa Calcichordates]]

'''Survival of the toughest:''' [[http://en.wikipedia.org/wiki/Sessile_animal Prehistoric sessile invertebrates]]

'''A treasure in the rocks:''' [[http://en.wikipedia.org/wiki/Foraminifera Foraminifers]], including [[http://en.wikipedia.org/wiki/Nummulite nummulites]]

!!Once upon a time... The Cambrian Animals

'''A floral aroma in the Cretaceous:''' Prehistoric [[http://en.wikipedia.org/wiki/Magnolia magnolias]], [[http://en.wikipedia.org/wiki/Nymphaeacaea water lilies]], and [[http://en.wikipedia.org/wiki/Arecaceae true palms]]

'''Grasslands, at last!:''' Prehistoric [[http://en.wikipedia.org/wiki/Poaceae grasses]]

'''Dinosaur trees:''' Prehistoric [[http://en.wikipedia.org/wiki/Ginkgophyta ginkgos]]

'''A resiny smell in the Jurassic:''' Prehistoric [[http://en.wikipedia.org/wiki/Pinaceae pines and firs]], [[http://en.wikipedia.org/wiki/Sequoioideae redwoods]], [[http://en.wikipedia.org/wiki/Yew yews]], [[http://en.wikipedia.org/wiki/Podocarp podocarps]], and [[http://en.wikipedia.org/wiki/Araucaria monkey puzzles]]

'''Palms, but not:''' [[http://en.wikipedia.org/wiki/Seed_fern Seed ferns]], [[http://en.wikipedia.org/wiki/Bennettitales pseudo-cycads]] and prehistoric [[http://en.wikipedia.org/wiki/Cycad cycads]]

'''The Mesozoic undergrowth:''' Prehistoric [[http://en.wikipedia.org/wiki/Fern ferns]] and [[http://en.wikipedia.org/wiki/Equisetum horsetails]]

'''The Paleozoic overgrowth:''' ''[[http://en.wikipedia.org/wiki/Lepidodendron Lepidodendron]]'' and ''[[http://en.wikipedia.org/wiki/Sigillaria Sigillaria]]''

'''The "first tree":''' ''[[http://en.wikipedia.org/wiki/Archaeopteris Archaeopteris]]''

'''The "first shoot":''' ''[[http://en.wikipedia.org/wiki/Cooksonia Cooksonia]]''

'''The greatest paleontological mystery:''' [[http://en.wikipedia.org/wiki/Ediacara_biota The Ediacara creatures]]

'''The first Earthlings:''' [[http://en.wikipedia.org/wiki/Stromatolite Prehistoric Stromatolites]] and other bacteria

* Extinct cephalopods have given fuel to many legends, even before paleontology itself was "invented" by [[http:/en.wikipedia.org/wiki/Georges_Cuvier Georges Cuvier]] at the end of the 18th century. Before that, those strange things today called fossils were believed to be Nature's jokes, the Earth's flowers, or other things (only Creator/LeonardoDaVinci correctly recognized their nature, but his discovery was long ignored). And then there are more specific legends about cephalopod fossils. [[UsefulNotes/StockDinosaursNonDinosaurs Ammonites]] were believed to be stony horns ("ammonite" comes from Amun, an Ancient Egyptian deity who was often portrayed with rams' horns), or petrified snakes.[[note]]Some had fun sculpting snake heads on the shells' extremities to make them look like snakes![[/note]] The lesser-known belemnites (technically belemnoids), with their straight pointed shape, were believed to be stony arrows, or even the Devil's fingers! Belemnites were cephalopods living in the Mesozoic era together with ammonites, and probably gave rise to squid. Like ammonites, only their shells are usually preserved. This shell was ''inside'' the animal's body and invisible in life; belemnites would resemble simple squid or cuttlefish if alive today. Their lifestyle was more active than ammonites, and they were probably able to do the same things modern squid do (spraying ink, swimming using the lateral "fins", catching prey with their suckers, seeing images with their eyes). True modern squid became widespread in the Cretaceous, and the first octopuses (''[[http://en.wikipedia.org/wiki/Proteroctopus Proteroctopus]]'' for example) were already around in the Middle Jurassic; these molluscs (called "coleoids") usually have no shell inside, or at least only a remnant of shell (ex. the famous cuttle-bone). Some Cretaceous squids were as large as a modern giant or colossal squid.

[[folder:Other invertebrates]]

'''Close to becoming reptiles:''' ''[[http://en.wikipedia.org/wiki/Proterogyrinus Proterogyrinus]]'', ''[[http://en.wikipedia.org/wiki/Westlothiana Westlothiana]]'', and ''[[http://en.wikipedia.org/wiki/Diadectes Diadectes]]''

'''A 50-year old mystery:''' ''[[https://en.wikipedia.org/wiki/Tullimonstrum Tullimonstrum]]'', aka the "Tully Monster".

'''Crabs and pseudo-crabs:''' Prehistoric [[http://en.wikipedia.org/wiki/Crustacea crustaceans]] and [[http://en.wikipedia.org/wiki/Xiphosura xiphosurans]]

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No other animal group has had a greater importance in paleontology than molluscs. Their fossils are extremely abundant, to the point that many rocky formations are composed mostly of fossilized mollusc shells. Among molluscs cephalopods deserve a mention apart, being much more "evolved" than the others. Together with arthropods, cephalopods are the extinct invertebrates you're most likely to see in media - at least, documentary media; you'll [[SmallTaxonomyPools rarely see]] a trilobite, ammonite, sea scorpion or nautiloid in Fictionland. If it happens, they'll be simple "ambient critters", and good luck if the animal [[NoNameGiven is mentioned]].

'''Stony arrows?:''' [[http://en.wikipedia.org/wiki/Belemnite Belemnites]] and extinct octopuses and squid

* Extinct cephalopods have given fuel to many legends, even before paleontology itself was "invented" by [[http:/en.wikipedia.org/wiki/Georges_Cuvier Georges Cuvier]] at the end of the 18th century. Before that, those strange things today called fossils were believed to be Nature's jokes, the Earth's flowers, or other things (only Creator/LeonardoDaVinci correctly recognized their nature, but his discovery was long ignored). And then there are more specific legends about cephalopod fossils. [[UsefulNotes/StockDinosaursNonDinosaurs Ammonites]] were believed to be stony horns ("ammonite" comes from Amun, an Ancient Egyptian deity who was often portrayed with rams' horns), or petrified snakes.[[note]]Some had fun sculpting snake heads on the shells' extremities to make them look like snakes![[/note]] The lesser-known belemnites (technically belemnoids), with their straight pointed shape, were believed to be stony arrows, or even the Devil's fingers! Belemnites were cephalopods living in the Mesozoic era together with ammonites, and probably gave rise to squid. Like ammonites, only their shells are usually preserved. This shell was ''inside'' the animal's body and invisible in life; belemnites would resemble simple squid or cuttlefish if alive today. Their lifestyle was more active than ammonites, and they were probably able to do the same things modern squid do (spraying ink, swimming using the lateral "fins", catching prey with their suckers, seeing images with their eyes). True modern squid became widespread in the Cretaceous, and the first octopuses (''[[http://en.wikipedia.org/wiki/Proteroctopus Proteroctopus]]'' for example) were already around in the Middle Jurassic; these molluscs (called "coleoids") usually have no shell inside, or at least only a remnant of shell (ex. the famous cuttle-bone). Some Cretaceous squid were as large as a modern giant squid.

----

"Fish" is a catch-all word containing all non-tetrapod vertebrates; that is, all backboned animals which are ''not only'' fully-aquatic, but descend from fully-aquatic ancestors as well. Ichthyosaurs, plesiosaurs, mosasaurs and dolphins aren't fish, just because they ''did'' descend from land-living creatures (except they are... in the same way birds are dinosaurs, but in this case even humans are fish!). There are only two groups of fish which are still successful today: sharks and ray-finned fish. Not so in Prehistory, as you'll get soon.

'''Shark Tales:''' ''[[http://en.wikipedia.org/wiki/Hybodus Hybodus]]'', ''[[http://en.wikipedia.org/wiki/Ptychodus Ptychodus]]'', ''[[http://en.wikipedia.org/wiki/Cretoxyrhina Cretoxyrhina]]'', and prehistoric rays

* Foraminifers ("forams" for friends) are ''really'' a treasure in the rock, in all senses. They have helped confirm the deep impact theory of dinosaur extinction, their shells have contributed to the formation of sedimentary rocks around the world, and they are cool in their own right, with their immense variety of shapes. The biggest forams, the nummulites, look often like literal coins emerging from the rocks (''nummulus'' means "little coin" in Latin); they are used as index fossils for the Cenozoic era, and also created the material for the [[BuildLikeAnEgyptian Egyptian pyramids]]! But wait: what are actually the foraminifers? Originally, scientists thought they were molluscs or mollusc-like critters; today we know they weren't even true animals. They were protozoans, aka single-celled organisms with animal-like traits. Most other one-celled "animals" have left very little if any fossil material; the ancestors of ''Amoeba'', ''Paramecium'', ''Euglena'', ''Vorticella'', and so on are a mystery. Even the radiolarians: their shells are siliceous, and silicon usually dissolves before fossilising.

* These conifer-looking trees were a common site in the Paleozoic era from the late Devonian period up to the early Permian period, with the Carboniferous period being the peak of their diversity. Despite their looks, however, ''Calamites'' were actually distant relatives of modern horsetails, and thus, like with other early plants like it, were strictly tied to swampy environments. Their trunks were usually hollow and resemble modern bamboo with vertical growth lines from the base to the canopy, and each segment contained rows of branches with 25 needle-shaped leaves each. They were known to reproduce by directly cloning themselves from underground root structures called rhizomes, the only plant of its age to even do so, which allowed them to remain anchored to loose wet ground and spread rapidly. Their resemblance to Christmas trees lead to many paleontologists joking about if a time traveler were to spend the Christmas holidays in the Carboniferous, ''Calamites'' are the way to go.

* These conifer-looking trees were a common site in the Paleozoic era from the late Devonian period up to the early Permian period, with the Carboniferous period being the peak of their diversity. Despite their looks, however, ''Calamites'' were actually distant relatives of modern horsetails, and thus, like with other early plants like it, were strictly tied to swampy environments. Their trunks were usually hollow and resemble modern bamboo with vertical growth lines from the base to the canopy, and each segment contained rows of branches with 25 needle-shaped leaves each. They were known to reproduce by directly cloning themselves from underground root structures called rihzomes, the only plant of its age to even do so, which allowed them to remain anchored to loose wet ground and spread rapidly. Their resemblance to Christmas trees lead to many paleontologists joking about if a time traveler were to spend the Christmas holidays in the Carboniferous, ''Calamites'' are the way to go.

* These conifer-looking trees were a common site in the Paleozoic era from the late Devonian period up to the early Permian period, with the Carboniferous period being the peak of their diversity. Despite their looks, however, ''Calamites'' were actually distant relatives of modern horsetails, and thus, like with other early plants like it, were strictly tied to swampy environments. Their trunks were usually hollow and resemble modern bamboo with vertical growth lines from the base to the canopy, and each segment contained rows of branches with 25 needle-shaped leaves each. They were known to reproduce by directly cloning themselves from underground root structures called rihzomes, the only plant of its age to even do so, which allowed them to remain anchored to loose wet ground and spread rapidly. Their resemblance to christmas trees lead to many paleontologists joking about if a time traveler were to spend the christmas holidays in the Carboniferous, ''Calamites'' are the way to go.

* These beings, important in the modern world, are poorly known in paleontology. Their "bodies" fossilize very rarely, but they have been major components of both water and land ecosystems since the Paleozoic. On a side note, only bryophytes (mosses, hornworts and liverworts) can correctly be called "plants". Algae is an informal group of not very closely-related clades, some of which (cyanobacteria or blue-green algae) aren't even plants in modern systematics. Neither are fungi (mushrooms, toadstools, molds and yeasts), which can't even perform photosynthesis - they are actually more closely related to animals than to plants! And lichens are not even true organisms: they are the results of a symbiotic relationship between a fungus and an alga.

The creatures here are from the Precambrian, and lived/originated ''before'' the other organisms listed in all the other "Prehistoric Life" pages. Talking about them is hard matter even for the most skilled biologists. Our mind has trouble to imagine how the first living beings actually looked, even more how they lived... However, not everything is unknown to us.

* Prior to 1956, the general conscious was that complex life didn't really start appearing until the Cambrian explosion, but a landmark discovery in England that year proved just as wrong we where when the 560 million year old organism ''[[https://en.wikipedia.org/wiki/Charnia Charnia]]'' was found. Since then, a myriad of different creatures has been discovered to have lived in the so called Ediacaran period that existed between the [[https://en.wikipedia.org/wiki/Cryogenian Cryogenian Glaciation]] and the Cambrian explosion. Many experts often thought they were [[OurMonstersAreWeird neither plants nor animals]], but something different from both! Notable groups include the completely uniquely tri-radial [[https://en.wikipedia.org/wiki/Trilobozoa Trilobozoa]], the ribbed oval "bags" knows as [[https://en.wikipedia.org/wiki/Proarticulata Proarticulata]], the fern or sea-pen like [[https://en.wikipedia.org/wiki/Rangeomorph Rangeomorpha]] of which ''Charnia'' was a member and the, um..[[BuffySpeak 'fleshy spiral']] with the galaxy-sounding name ''[[https://en.wikipedia.org/wiki/Eoandromeda Eoandromeda]]''. But despite all these Ediacaran Biota (often improperly called "Ediacaran Fauna") had wildly different looks, they do have things in common that defines life from this era: they almost universally exhibit [[https://en.wikipedia.org/wiki/Glide_reflection glide reflection]] in their body plan, they appear completely unrelated to modern animals/plants/fungi as said above, they almost completely disappeared at the end of the Ediacaran period, and they where arguably completely sessile. Probably either filtering nutrients out of the water or "growing" on top of microbial mats which they feed on through "roots". This unique aspect of them has caused the group to sometimes be refereed to as ''The Garden Of Ediacara''. More of what we would call traditional animals also started to appear towards the end of the period; such as the slug-esque ''[[https://en.wikipedia.org/wiki/Kimberella Kimberella]]'' (which might also have been one of the first creatures capable of locomotion), the arthropod/trilobite like ''[[https://en.wikipedia.org/wiki/Spriggina Spriggina]]'' and the Cnidarian/jellyfish relative known as ''[[https://en.wikipedia.org/wiki/Haootia Haootia]]'', rather similar to the modern freshwater [[https://en.wikipedia.org/wiki/Hydra_viridis Green Hydra]].

* One-celled organisms are usually not preserved in fossil records (the aforementioned foraminifers are a well-known exception). However, we're sure the first Earthicans were bacteria. [[note]]For [[GeniusBonus expert readers]]: we're talking about bacteria in broader sense, including also the Archaea.[[/note]] They have been the simplest form of life, even lacking the nucleus which is the hallmark of the Eukarya - that is, animals + plants + fungi + algae + protozoans + other less-known organisms, ''all'' with nucleate cells. Some bacteria, the photosynthetic cyanobacteria (improperly called "green-blue algae") have built strange rocky structures called stromatolites (they produce them still today); the most ancient stromatolites are from 2,000 million years ago, ''three'' times earlier than the first multi-celled organisms. They are among the most ancient form of life that has left some fossils. It's worthy noting that parasitic bacteria (those that carry diseases) could only have appeared ''after'' multi-celled organisms: otherwise [[FridgeLogic which creature could have they infected?]] The same about the non-living viruses: [[note]] They are basically simple aggregates of proteins, lipids, and a bit of DNA or RNA capable to self-replicate: if we consider them "living", then we'd do the same with the chromosomes inside our cells, which are also aggregates of DNA and proteins able to replicate themselves.[[/note]] they should have appeared only ''after'' true living things for the same reasons (Some viruses infect bacteria, mind this). How life as a whole has originated is one of the most fascinating fields within human knowledge, but here we're outside paleontology and science in general. This is mainly speculation and philosophy, even though molecular biologists are doing great efforts to found the answer.

** [[https://en.wikipedia.org/wiki/RNA_world The RNA world]] about as far as we can look back. The RNA world is a well founded hypothesis - it has enough evidence to be generally believed, but insufficient to be considered proven. In the modern world, DNA codes genes. Genes are copied to messenger RNA. Messenger RNA is read by ribosomes to create proteins. Almost all the functions of the cell are performed by proteins, including duplicating DNA, copying DNA to RNA, and most of the ribosome is protein. This works great, but how could it start? DNA can't replicate without proteins, and proteins can't be made without the instructions in DNA. However, RNA can both store information ''and'' catalyse reactions. Although it would be grossly inefficient by modern standards, life based on RNA with no DNA and no proteins is quite plausible. The RNA world hypothesis is that such RNA life existed, and is ancestral to modern life. Evidence for this is functional RNA (RNA which does stuff directly, rather than simply being instructions to ribosomes) performs just a few cellular functions, but very central critical ones. Most central is that RNA forms the reactive core of the ribosomes.

* For the majority of the Age of Reptiles, however, most land plants had no flowers. Non-flowering plants belonged to two main groupings: those reproducing with seeds, and those reproducing with spores. The former are traditionally called "gymnosperms" ("naked seeds", due to the fact that their seeds aren't enclosed in fruits like flower plants' are), but are actually several groups of plants not particularly closely related to each other. The most familiar gymnosperms are, obviously, the conifers (see below). In paleo-books, however, you'll often see mention of ''[[http://en.wikipedia.org/wiki/Ginkgo_biloba Ginkgo biloba]]''. This is, indeed, the ''only'' surviving member of a whole group of seed plants (the Ginkgophyta) that were among the dominant greens in the Mesozoic. Its special status results in the ginkgo often being cited as a ''living fossil''. However, it doesn't look like a pine or a fir: with its wide leaves and soft, fruit-like seeds, it resembles a typical flowering plant that you just never catch flowering. Indeed, ginkgophytes are probably the closest relatives of angiosperms. Even though the modern ginkgo is grown around the world as an ornamental tree, its wild ancestor lives only in East Asia.

* In some ways, Mesozoic vegetation wasn't so different from ours. True, most land plants in dinosaur times were pine-like, palm-like or fern-like, and flowering plants were still a minority... but conifer forests are still widespread today in northern territories. But if our time machine could bring us to the Carboniferous (aka the Coal Age, 100 million years before the Triassic), landscapes would ''really'' look like a sort of Otherworld. At the time, all the plant groups mentioned above were either a small portion of Earth's vegetation, or hadn't yet appeared. The dominant plants were the so-called lycopods - named after ''[[http://en.wikipedia.org/wiki/Lycopodium Lycopodium]]'' (lit. "wolf foot"), a tiny plant which is one of the few examples still surviving. Many of them would resemble extraterrestrial trees if alive today: ''Lepidodendron'' (lit. "scaly tree") and ''Sigillaria'' are two often-cited examples. Their trunks were indeed scaly, they sometimes had only ''two'' branches, and some grew up to a hundred feet tall! Despite their massive aspect, they were quite fragile giants: giant lycopods were easily felled by the frequent Carboniferous storms. This was less a liability for these species than it would be for modern trees, because even giant lycopods grew rapidly, with a life cycle of no more than 10 or 15 years. The rotting logs then carbonized, becoming the fossil coal we burn today (hence "Carboniferous", meaning "coal-bearing"). It's worth noting that lycopods, ferns and horsetails have always been strictly tied with water; their spores can develop in adult individuals only in humid habitats, and this explains why they were so common in the Carboniferous swamp world. Then, in the following Permian period, the Earth mostly dried out, and giant lycopods weren't able to survive the change. Seed plants have become the more successful plant group since then: seeds are a bit like the reptiles' and insects' shelled eggs, well-adapted to survivie in arid environments.

* Sometimes it seems paleontologists have fun making unwilling jokes with scientific names. While the traditional "first bird" is called ''[[UsefulNotes/StockDinosaursTrueDinosaurs Archaeopteryx]]'', one of the first land plants ever appeared is the almost homonymous ''Archaeopteris''! But wait, ''Archaeopteryx'' means "ancient wing", ''Archaeopteris'' means "ancient fern". This plant lived in the Devonian (before the Carboniferous), just when the proto-amphibian ''Ichthyostega'' made the first step on dry land; it was one of the first terrestrial plants to develop the size of a tree. Since at the time land animals were very few and mostly carnivorous or detritivorous, ''Archaeopteris'' and its relatives were able to spread worldwide but never far from water, just like amphibians did. Their appearence was that of a tree fern: indeed, the fern-like is considered one of the most primitive body plans among terrestrial plants.

* However, plants went on land ''before'' the amphibians. In the Silurian period (before the Devonian) there were already some aquatic plants (ex. the Psilophytes) emerging out of water; ''Cooksonia'' is an often cited example. These tiny plantlets had their roots still underwater, but their "branches" grew out of the water level, capturing extra light. Terrestrial plants are actually very evolved creatures and have done a hard work to create their adaptations to survive outside the liquid element. Among them, a vascular system (that is, tiny vessels for the flow of the lymph), waterproof "skin", and fibres to make their stalks more robust against gravity.

* This species was first described in 1843, and for the longest time experts couldn't decide ''what'' it was. Many thought it was a conifer tree (its name means "First yew"), others thought it was a giant aquatic alga. It wasn't until 2007 that scientists confirmed it was indeed a [[FungusHumongous giant terrestrial fungus]]! Since this thing grew up to 8 meters, it would've been the tallest organism of its time. Many are still confused as to how such an organism could grow like that without photosynthesis.

* These so-important living beings in modern world are very little known in paleontology. Their "bodies" fossilize very rarely, but they surely have been main components of both water and dry land ecosystems since the Paleozoic. However, only bryophytes (mosses, hornworts and liverworts) can be called "plants" without going in error. Algae (seaweed) and fungi (mushrooms, toadstools, moulds, yeasts) are NOT true plants in modern systematics (fungi cannot even perform photosynthesis!). And lichens are not even true organisms: they are the results of a symbiotic relationship between a fungus and an alga.

When thinking about fossils, we tend to think about animals. But plants have also left many remains, some of them just as spectacular as the animal ones (think about the [[http://en.wikipedia.org/wiki/Petrified_wood petrified woods]], the most famous being that in Arizona), and others less striking but even more significant, such as prints of leaves (very common in some deposits) and even the fossilized ''pollen'' which has allowed us to understand not only the composition of ancient flora, but even the climate they lived in. And, naturally, the aforementioned [[Film/JurassicPark amber]] which has often caught insects inside.

* In the Early Mammal Age landscapes were already similar to those surrounding us today... except for one thing: grasslands were still totally missing. Prairies and savannah appeared only 30-20 million years ago in the middle of the Cenozoic. Grasses were ''already'' living in the Cretaceous, but they still didn't form grasslands, they grew isolated within the undergrowth. Grasslands have had a crucial role in Earth's ecosystems: all modern herbivorous mammals living in the modern African savannah (just to make one example) were able to evolve ''just'' thanks to grass. They developed special teeth to cope with this especially harsh green food, and thanks to the scarcity of trees, they were able to become bigger and faster. We humans have to be grateful to the grasses, too. All cereals and most fodder belong to this family of plants, as well as bamboo and sugar cane, other than the common grass naturally. However, their importance has been even greater than what you might think: if the grasses didn't evolve million years ago... you would not be here to read this. Simply, without grasslands, the human race still would look like big apes. (see [[UsefulNotes/PrehistoricLIfeMammals in the Mammal section]]).

* In the Dinosaur Age, however, most land plants had no flowers. Non-flowering plants belonged to two main ensembles: those reproducing with seeds, and those reproducing with spores. The former are traditionally called "gymnosperms", but are actually more than one group of plants not particularly closely related to each other. The most familiar gymnosperms are, obviously, the conifers (see below). In paleo-books, however, you can often read the name "''[[http://en.wikipedia.org/wiki/Ginkgo_biloba Ginkgo biloba]]''". This is, indeed, the ''only'' surviving member of a whole group of seed plants (the Ginkgophyta) that was among the dominant greens in the Mesozoic. Its special status makes the ginkgo often cited as a ''living fossil''. However, it doesn't look like a pine or a fir: with its wide leafs and fruit-like seed, it resembles a normal-looking flowering plant. Indeed, ginkgophytes are probably the closest angiosperm relatives. Even though the modern ginkgo is widespread around the world as a ornamental tree, its wild ancestor lives only in Eastern Asia.

* Fictional media typically make us believing the trees from the Mesozoic were ''all'' palm-shaped. If non-palmlike tree appear, they usually have the shape of an angiosperm. Pines, firs, spruces, larches, cypresses and cedars are usually unseen in Fictionland... maybe because are usually associated with ''cold'' in the writers' mind (while OneMillionBC is ''always'' a very hot world filled with volcanoes....). However, in RealLife things were very different. Conifers were among the dominant plant groups in the whole Mesozoic, and a common food for camarasaurs, camptosaurs, centrosaurs, cetiosaurs, chasmosaurs, corythosaurs, and so on. However, there were not only pines and firs [[note]]better, their ancestors adapted to a warmer climate than the modern ones.[[/note]] at the time: more common were some kinds of conifers which are rare or extinct today. For example, the araucarians (monkey puzzles), the podocarps, the yews, and the more spectacular of all, the sequoia trees. [[note]]Modern sequoias are nicknamed "mammoth trees" for their size.... but a mammoth would appear ''really'' a midget next to its green namesake! [[/note]] If you think sauropods were the real titans of the Jurassic, think again: a ''[[UsefulNotes/StockDinosaursTrueDinosaurs Giraffatitan]]'' near a redwood would appear like a house cat near a fully grown man.

'''Palms, or not?:''' [[http://en.wikipedia.org/wiki/Seed_fern Seed ferns]], [[http://en.wikipedia.org/wiki/Bennettitales pseudo-cycads]] and prehistoric [[http://en.wikipedia.org/wiki/Cycad cycads]]

* These are the Mesozoic seed plants that more resemble the ones seen in the fictional Dinosaur Age. They ''did'' resemble palm trees, but were NOT related at all with them. Cycads are the only ones still living, often used to embellish our cities. Bennettitales or cycadeoids ("pseudo-cycads") went extinct at the end of the Mesozoic. These two groups were very abundant at the dinosaur times, but were already present before the Triassic (as well as the little-known Cordaitales, maybe the ancestors of the conifers). About pteridosperms (the "seed ferns"), they are so called because of their external look, but were ''not'' true ferns: ferns do reproduce with spores. Seed ferns were among the very first seed plants ever appeared, in the Devonian, and survived until the Cretaceous. One of them, the Triassic ''[[http://en.wikipedia.org/wiki/Glossopteris Glossopteris]]'', was widespread in the southern portion of the Pangaea supercontinent. This pteridosperm has been used to demonstrate the Pangaea hypothesis itself: its fossils have been found in every southern modern continent, showing landmasses were still united at the start of the Dinosaur Age (see also ''[[UsefulNotes/StockDinosaursNonDinosaurs Lystrosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Mesosaurus]]'' in other pages).

* One of the worst errors in popular media (sometimes even the documentary ones) is to portray ''grasslands'' [[MisplacedVegetation in the Mesozoic]]. Arguably, writers think grass is the simplest kind of plant ever... thus, the first ever appeared on Earth. As seen above, grass are actually the ''most evolved'' plants and among the latest to become widespread on our planet. In the Dino Age, the dominant small-sized land plants were much, much more primitive: ferns, fern relatives and horsetails. These are collectively called pteridophytes and their modern descendants still make a wide portion of the undergrowth in many forests. In the Mesozoic, ferns and horsetails already made the forests' undergrowth, but also made true "prairies" where trees were absent. Only in the Mammal Age fern prairies were definitively substituted by grass prairies. But don't think ferns and horsetails were always small: in Prehistoria there were also giant horsetails and tree ferns, both deceptively similar to trees. In some places, they still live today: the 10m tall ''[[http://en.wikipedia.org/wiki/Equisetum_giganteum Equisetum giganteum]]'' is still growing in tropical landscapes. And tree ferns are still present in Australia and New Zealand -- to the point that in the latter country they have become a national symbol, just like the kiwis. Indeed, the LandDownUnder and its neighbor archipelago are a real mine of "living fossils": not only the platypus, the kiwi, or the tuatara...

* After all, Mesozoic vegetation wasn't so different than ours. Right, most land plants at the dinosaur times were mostly pine-like, palm-like or fern-like, and flowering plants were still a minority... but widespread conifer forests are still present today in northern territories. But if our time machine could bring us to the Carboniferous (aka the Coal Age, 100 million years before the Triassic), landscapes would appear REALLY a sorta Otherworld. At the time, all the plant groups cited so far were either a small portion of Earth' vegetation, or they haven't still appeared. The dominant plants were the so-called lycopods -- named after ''[[http://en.wikipedia.org/wiki/Lycopodium Lycopodium]]'' (lit. "wolf foot"), a tiny plantlet which is one of the few kinds surviving today. Many of them would resembled extraterrestrial trees if alive today: ''Lepidodendron'' (lit. "scaly tree") and ''Sigillaria'' are two often cited examples. Their trunk was indeed scaly, they sometimes had only ''two'' branches; and some were huge, taller than a building! Despite their powerful look, they were quite fragile giants: giant lycopods easily fell down during the frequent Carboniferous storms. The rotting logs then carbonized, becoming the fossil coal we burn today (hence "Carboniferous", meaning "coal-making"). It's worth noting lycopods, ferns and horsetails have always been strictly tied with water; their spores can develop in adult individuals only in humid habitats, and this explains why they were so common in the Carboniferous swamp world. Then, in the following Permian period the Earth mostly dried out, and giant lycopods weren't able to survive the change. It was seed plants that have become the more successful plant groups since that: seeds are a bit like the reptiles' and insects' shelled eggs, well-adapted to sprout in arid environment.

* If you ask a paleontologist what are the most common vertebrate fossils, (s)he'll answer you "shark teeth". However, these teeth are usually found isolated - ironically, the remaining skeletons are among the rarest fossil finds (sharks' cartilage doesn't fossilize well, unlike bone). Even though sharks make up only a small percentage of modern fish species (about 5%), they were a very successful group in the past, even more diversified than they are today. But stop a moment. What is a shark, exactly? In common sense, sharks are things like the great white or the bull shark, but zoologists often use this word to indicate every cartilaginous fish, or more technically, every Chondrichthyian. Palaeontologists usually give the same meaning to "shark", too. The first-ever sharks appeared in the Devonian period 400 million years ago, and since then have changed very little: sharks are often cited as "living fossils". More precisely, the modern kinds of shark appeared in the Cretaceous: earlier sharks were only distantly related to them. Examples are ''Cladoselache'', ''Stethacanthus'', and ''Xenacanthus'' (once also called ''Pleuracanthus''), all from the Devonian period, and also a little-known modern fish, the deep sea chimaera (also called ratfish or rabbitfish). The latter has preserved to this day the mixed shark/bony fish anatomy of the acanthodians and the earliest rayfins. ''Cladoselache'' ("branch shark") was more like a true shark, with uncovered gills and tooth-like scales covered in enamel (its fossils have preserved prints of soft tissues), but its mouth was strangely placed at the front of its head like the modern, unrelated whale shark. ''Xenacanthus'' and ''Stethacanthus'' were more bizarre. The former had an eel-like body and a long filament protruding from its head (its name means "strange spine"); the latter is nicknamed "ironing-board shark" from its flat head prominence (not a dorsal fin) with many dentines on the top. Possibly only males had these things, which resemble the much smaller tubercle of the male chimaera (if so, they would have been courtship devices). But the perhaps weirdest "shark" ever is ''Helicoprion'' ("helix saw"), the "whorl-toothed shark", whose teeth were arranged in a spiral coil inside its mouth! It now appears that both ''Helicoprion'' and ''Stethacanthus'' may actually belong to the chimaera lineage, thus not proper sharks. Other early chondrichthyans, ''Falcatus'', ''Harpagofutator'', and many others, also showed strange prominences above their heads.

!!Bugs Everywhere! TRUE INSECTS

* Crinoids, echinoids, asteroids[[note]]NOT [[AsteroidThicket those]] asteroids![[/note]], ophiuroids, holoturoids, blastoids, cystoids, carpoids: [[RiddleMeThis who's the intruder?]] To some extent the carpoids (see the following paragraph); all the others are confirmed to have been echinoderms. The asteroids ("star-like") are the starfish; ophiuroids are nicknamed "brittle stars" or "serpentine stars"; the echinoids ("husk-like") are the sea urchins and sand-dollars; while the holoturioids are the sea cucumbers or trepang. Thanks to their hard "skeleton", all these groups (except for the soft-bodied sea cucumbers) are common fossils, and have roamed the seas since the start of the Paleozoic. However, we're going to talk more about other three less-familiar groups of echinoderms: crinoids, blastoids and cystoids. Crinoids ("sea lilies") are the only ones still living, but are today a rarer sight than the four groups above; like brachiopods, they are considered "living fossils". They're not-very-movable filter feeders, and like all echinoderms, they more resemble plants than animals: symmetrically rayed and with several "arms" that make them look like ferns or flowers (hence "sea lily"). Adult echinoderms lack eyes, limbs and heads (but have a mouth nonetheless) and they usually lack distinct right and left sides to their bodies - however, their tiny planktic larvae ''do have'' bilateral symmetry. The astonishing thing is, echinoderms are among the closest relatives of vertebrates, being Deuterostomes like us and not Protostomes (like most invertebrates). Blastoids and cystoids are known exclusively from fossils, and were similar to crinoids but without the "arms"; their lifestyle was probably similar to the sea lilies'. Also worthy of mention are the (also extinct) [[http://en.wikipedia.org/wiki/Edrioasteroid edrioasteroids]], which were perhaps similar to sand dollars or sea urchins.

When thinking about fossils, we automatically think about ''animals''. But also plants have left many remains, some of them just as spectacular than the animal ones (think about the [[http://en.wikipedia.org/wiki/Petrified_wood petrified woods]], the most famous being that in Arizona), other less-striking but even more significant, such as prints of leaves (very common in some deposits) and even the fossilized ''pollen'' which has allowed us to understand not only the composition of ancient flora, but even the climate they lived in. And, naturally, the aforementioned [[Film/JurassicPark amber]] which has often caught insects inside, of course.

'''A flowering smell in the Cretaceous:''' Prehistoric [[http://en.wikipedia.org/wiki/Magnolia magnolias]], [[http://en.wikipedia.org/wiki/Nymphaeacaea water lilies]], and [[http://en.wikipedia.org/wiki/Arecaceae true palms]]

* The most familiar plants today are the angiosperms aka flowering plants, including most modern trees, bushes, herbs, but also apparently non-flowering critters such as grass, palms, bamboos, and even some "seaweed" (''[[http://en.wikipedia.org/wiki/Posidonia_oceanica Posidonia]]''). But as a group, they appeared only in the Cretaceous. Or, at least, became widespread only in that period. In modern taxonomy the angiosperms are called magnoliophytes (literally magnolia plants). Indeed, the magnolia was one of the earliest flowering plants ever appeared, in the lower Cretaceous. This is the most commonly shown angiosperm in paleo works, which often portray herbivorous dinosaurs like ''[[UsefulNotes/StockDinosaursTrueDinosaurs Iguanodon]]''s and ''[[UsefulNotes/StockDinosaursTrueDinosaurs Triceratops]]''es eating magnolia leaves. [[note]] It was hypothesised that dinosaurs have actually helped flowering plants to became more widespread [[/note]]. Among the other earliest angiosperms are water lilies. The first palm trees also appeared in the Cretaceous (but note that most Cretaceous palm-looking trees were NOT palms, see further). However, most modern flowering greens - roses, apples, figs, oaks ad infinitum - appeared (or became a main component of the vegetation) only AFTER the dinosaur extinction. The angiosperms' success is tied to their relationship with pollinating animals, especially insects (see in the Arthropod section above), but also to those mammals/birds which still aid them to disperse their seeds by eating their fruits, or by other means. However, some flowering plants returned again to traditional strategies, using the WIND to disperse their pollen like the more archaic pines/firs do. Among them, ironically, are the most evolved and successful ones: the Poaceae, aka the grasses. See below.

The Cambrian. The first period of the Paleozoic era, in which the famous [[http://en.wikipedia.org/wiki/Cambrian_explosion Cambrian explosion]] of life happened. The less famous fact is that we're ''unbelievably lucky'' to know anything about this remote event. At that time, animals just were starting to achieve hard parts in their bodies, and we already know that, usually, soft-bodied organisms don't fossilize at all. By astounding luck, one of the greatest exceptions to this rule are some deposits from the Cambrian period: it almost seems Ol'Mother Nature [[BecauseDestinySaysSo did this deliberately for us]]. The most famous and historically relevant is the [[http://en.wikipedia.org/wiki/Burgess_Shale Burgess Shale]] in British Columbia (first found in 1909 by Charles Walcott), but others are known (for example that of Chengjiang, China). For obvious reasons, our first question is: which were the first animals (not counting protozoans) that thrived in our oceans? Well, the answer isn't simple, but we can divide them into two groupings. One is made of those clades either still alive today or that went extinct several ages after the Cambrian: among the former, most non-arthropod/non-cephalopod invertebrate groups already mentioned; among the latter, the trilobites. We'll talk here about the second grouping: many Cambrian invertebrates were indeed ''exclusively of the Cambrian'' and didn't survive long, not even reaching the following period, the Ordovician - in which the most famous Paleozoic critters, sea scorpions, nautiloids, ostracoderms, etc. appeared. Thus, many of them are classically viewed as RealLife examples of OurMonstersAreWeird by paleo-fanatics. We still know very very little about their lifestyles, but their appearance is extraordinarily well-known, because these Cambrian deposits ''have preserved soft bodies''; not only that, they have preserved them very well! It would take too long to mention [[http://en.wikipedia.org/wiki/Fossils_of_the_Burgess_Shale all the members]] of the Cambrian fauna: see [[http://www.trilobites.info/triloclass.htm the image here]] to get an idea. The large guy in the center is immediately recognizable, by far the biggest creature in this fauna: ''[[UsefulNotes/StockDinosaursNonDinosaurs Anomalocaris]]''. Of course it is the most portrayed Cambrian animal in documentaries and illustrations, often called "[[SeaMonster the first sea monster to appear on Earth]]". Actually, if alive today, the "terrible" anomalocaridid would look vaguely like a lobster, 3 ft long, shell-less and pincer-less... nothing dangerous for a tough-boned, tough-muscled, tough-skinned mammal such as a human. Apart from ''Anomalocaris'' we can mention other three invertebrates which are stock in drawings: ''[[http://en.wikipedia.org/wiki/Hallucigenia Hallucigenia]]'', ''[[http://en.wikipedia.org/wiki/Opabinia Opabinia]]'', and ''[[http://en.wikipedia.org/wiki/Pikaia Pikaia]]''. The first has a name that means "hallucination generator"; it was a sort of "worm" with long paired spikes on its back, of uncertain purpose, and long soft paired legs. The reconstruction of ''Hallucigenia'' was an astounding ScienceMarchesOn tangle for many years: it was first reconstructed ''upside-down'', with the dorsal spikes believed to be legs, and the legs pointing upwards and thought to each end with a small mouth! Its taxonomy is uncertain, but it's tentatively classified as a lobopod, a distant relative of arthropods. ''Opabinia'' was related to ''Anomalocaris'', but even weirder-looking; perhaps no other fossil animal more resembles a fictional space alien. It had ''five eyes'' placed in circular fashion on its head, and a pincer at the end of a long, flexible proboscis, often mistaken for the mouth, which was actually located behind the proboscis. When it was first described, many paleontologists didn't believed its describer was serious and openly laughed at it! But the most important find is the third guy, ''Pikaia'': despite its rather insignificant slug-like appearance, it is the most well-known vertebrate ancestor, a sort of prehistoric relative of our [[http://en.wikipedia.org/wiki/Lancelet lancelet]] (the closest extant relative of vertebrates). This relevance has made ''Pikaia'' one of the unofficial symbols of evolution, just like the ur-amphibian ''Ichthyostega'', the ur-bird ''Archaeopteryx'' and the ur-horse ''Eohippus''. But wait... have you sees these critters in TV at least once? Unlikely, even if you watched ''Series/WalkingWithMonsters''. In this RuleOfCool-filled show, the ''only real'' Cambrian invertebrate to appear is... Guess what? Well, the superpredator ''Anomalocaris'' of course! The other two invertebrates that show up are... a modern jellyfish and an [[AnachronismStew anachronistical phacopid trilobite]] - remember that phacopids first evolved in the Ordovician, while Cambrian trilobites looked very different from the classic image we have when thinking about these animals. The absence of such awesome animals like ''Opabinia'' and ''Hallucigenia'' - and still others, like the multi-tentacled ''[[http://en.wikipedia.org/wiki/Wiwaxia Wiwaxia]]'', the trilobite-like ''[[http://en.wikipedia.org/wiki/Marrella Marrella]]'', the caterpillar-like ''[[http://en.wikipedia.org/wiki/Aysheaia Aysheaia]]'', the lobster-like ''[[http://en.wikipedia.org/wiki/Sidneyia Sidneyia]]'', the "hairy worm" ''[[http://en.wikipedia.org/wiki/Canadia Canadia]]'', etc. - is another egregious example of a [[TheyWastedAPerfectlyGoodPlot missed opportunity]]. Speaking of ''Pikaia'', this time its absence is less of a problem: the aforementioned proto-vertebrate ''Haikouichthys'' filled its role. And another thing: if you read the list of creatures from the Burgess Shale, you'll note almost all animals (the main exception being ''Anomalocaris'') have uncommonly short scientific names, most of them ending in '''-a'''. Rather amusing to read, and - let's face it - a ''true'' oasis of happiness among so many other unutterable, absurdly-difficult names.

There is not much to say about the portrayal of extinct non-arthropod/non-cephalopod invertebrates in media: they [[SeldomSeenSpecies rarely appear]] even in books and documentaries, much less in Fictionland, and when they do, they are almost [[NoNameGiven never named]] (except sometimes for the names of each group, but only in popular science works). As an example, the original Disney's ''Disney/{{Fantasia}}'' showed several ''modern'' critters to symbolize the early evolution of invertebrates, but [[SmallTaxonomyPools few or no]] ''truly'' prehistoric ones. The ''Walking With'' series did the same: only modern jellyfish, sponges and sea urchins appear, all live-action. Indeed, many modern invertebrate groups have populated our seas since the Cambrian Period, but many others are extinct today. Among modern land arthropods expect to see dragonflies, scorpions, centipedes, spiders, cockroaches, beetles, and sometimes crickets. They will be oversized: [[BigCreepyCrawlies roaches the size of a rat, scorpions as big as cats]], and so on. Finally, let's not forget a staple in every Paleozoic or Mesozoic sea: a jellyfish, used as the symbol of the most ancient forms of life.

* Crinoids, echinoids, asteroids, [[note]] NOT [[AsteroidThicket those]] asteroids! [[/note]] ophiuroids, holoturoids, blastoids, cystoids, carpoids: [[RiddleMeThis who's the intruder?]] To some extent the carpoids (see the following paragraph); all the others were confirmed echinoderms. The asteroids ("star-like") are the starfish; ophiuroids are nicknamed "brittle stars" or "serpentine stars"; the echinoids ("husk-like") are the sea urchins and sand-dollars; while the holoturioids are the sea cucumbers or trepang. Thanks to their hard "skeleton", all these groups (except for the soft-bodied sea cucumbers) are common fossils, and have roamed the seas since the start of the Paleozoic. However, we're going to talk more about other three less familiar groups of echinoderms: crinoids, blastoids and cystoids. Crinoids ("sea lilies") are the only ones still living, but are today a rarer sight than the four groups above; like brachiopods, they are considered "living fossils". They have been not-very-movable filter feeders, and like all echinoderms they resemble more plants than animals: symmetrically rayed and with several "arms" that make them looking like ferns or flowers (hence "sea lily"). Adult echinoderms lack eyes, limbs, heads (but have a mouth nonetheless) and they usually lack a right/left side of their body - however, their tiny planktic larvae ''do have'' bilateral symmetry. The astonishing thing is, echinoderms are among the closest relatives of vertebrates, being Deuterostomes like us and not Protostomes (like most invertebrates). About blastoids and cystoids, they are exclusively fossil, were similar to crinoids but without the "arms"; their lifestyle was probably like the sea lilies'. Also worthy mention were the (exclusively fossil as well) [[http://en.wikipedia.org/wiki/Edrioasteroid edrioasteroids]], perhaps similar to sand dollars or sea urchins.

* In Prehistory, some odd-looking invertebrates were even closer relatives of us vertebrates than echinoderms themselves: graptolites and calcichordates (or homalozoans). Graptolites are among the most common fossils in the Paleozoic, and used as index fossils alternatively to trilobites. They resembled floating water plants, but the "plant" was ''not'' the whole organism. They were colonial animals like modern corals, and the single individuals were actually ''inside'' the colony. Like brachiopods and crinoids, graptolites too were passive filter feeders. About calcichordates (remember, they are the carpoids above), they have been variably classified as primitive echinoderms, graptolite relatives, or even true chordates (that is, the group including sea-squirts & relatives + lancelets + vertebrates aka US). Calcichordates lived in the bottom seas, were movable animals (and bilaterally symmetrical unlike a typical echinoderm), with an armor and a sort of "tail". [[note]]Note that only chordates have a tail: tail-looking structure in invertebrates are ''never'' real tails: even the scorpion's one is just the extremity of its abdomen, with the anus ''near'' the sting! [[/note]] However, one of the most depicted calcichordate, ''[[http://en.wikipedia.org/wiki/Cothurnocystis Cothurnocystis elizae]]'', lost the bilateral symmetry altogether for inexplicable reasons.

* This is a merciless law even in palaeontology. Only hard parts of the organisms' bodies usually fossilized: bones, shells, armors, jaws, teeth, and whatnot. Many modern invertebrate groups which haven't tough elements left little fossil record (if they did). For examples, most "worms" (annelids aka segmented worms, nematodes aka round worms, platyhelmintes aka flatworms, nemertheans aka ribbonworms, and many others) are virtually unknown in paleontology, and their evolution is only a guess. This is also true for coelenterates - that is, the cnidarians (jellyfish, sea anemones, hydrae, siphonophores) and the ctenophores (comb jellies). At least, the totally soft ones; fortunately, corals (which are also cnidarians) build tough external skeletons that fossilize well, and their extinct relatives are well-known since the start of the Paleozoic. The same about the unfamiliar bryozoans (moss animals), very similar but not related at all with corals but with the brachiopods. Finally, the enigmatic sponges (which many zoologist hardly consider real animals) are also frequent fossils. They too have had an inner "skeleton" made of limestone (and sometimes glass-like silicon or a horny material, but they usually don't fossilize); one extinct group of possible sponge relatives were the [[http://en.wikipedia.org/wiki/Archaeocyatha archaeocyathans]], which became the planet's first reef-building animals in the Early Cambrian.

* Foraminifers ("forams" for friends) are ''really'' a treasure in the rock, in all senses. They have contributed to confirm the deep impact theory about dinosaur extinction; their shells have contributed to form several sedimentary rocks around the world; and they are cool on their own, with their immense variety of shapes. The biggest forams, the nummulites, look often like literal COINS emerging from the rocks ("nummus" means coin in Latin); they are used as index fossils for the Cenozoic era, and have also created the material for the [[BuildLikeAnEgyptian Egyptian pyramids]]! But wait: what are actually the foraminifers? Originally, scientists thought they were molluscs or mollusc-like critters; today we known they weren't even real animals. They were "protozoans", aka single-celled organisms with animal traits. Most other one-celled "animals" have left very few fossil material (if they did); the ancestors of ''Amoeba'', ''Paramecium'', ''Euglena'', ''Vorticella'', and so on are a mystery. Even the radiolarians: their shell is siliceous, and silicon usually dissolves before fossilising.

!!Once upon a time... CAMBRIAN ANIMALS

Cambrian. The first Paleozoic period, in which the famous [[http://en.wikipedia.org/wiki/Cambrian_explosion Cambrian explosion]] of life happened. The less known thing is, we humans are ''unbelievably lucky'' if we know that remote event. At that time, animals just were starting to achieve hard parts in their body, and we already know that, usually, soft-bodied organisms do not preserve at all. The astounding luck is, one of the greatest exceptions of this rule are ''just some deposits from the Cambrian period.'' : it almost seem Ol'Mother Nature [[BecauseDestinySaysSo has done this deliberately for ourselves...]]. The most famous and historically relevant is the [[http://en.wikipedia.org/wiki/Burgess_Shale Burgess Shale]] in British Columbia (first found in early 1900 by Charles Walcott), but still others are also known (for example that of Chengjiang, China). For obvious reason, our curiosity now reaches the top: which were the first animals (not counting protozoans) that thrived in our oceans? Well, the answer is not simple: we can divide them in two ensembles. One is made from those groups either still alive today or extinct several ages after the Cambrian: among the former, most non-arthropod / non-cephalopod invertebrate groups already seen; among the latter, the trilobites. We'll talk here about the second ensemble: many Cambrian invertebrates were indeed ''exclusive of the Cambrian'' and didn't survive long enough, not even to reach the following period, Ordovician - in which the most famous Paleozoic critters: sea scorpions, nautiloids, ostracoderms etc. appeared. Thus, many of them are classically viewed as RealLife examples of OurMonstersAreWeird by paleo-fanatics. We still know very very few things about their lifestyle, but their appearance is extraordinarily well-known, because these Cambrian deposits ''have preserved soft bodies''; not only that, they have preserved them very well! It would be too long to mention [[http://en.wikipedia.org/wiki/Fossils_of_the_Burgess_Shale all the members]] of the Cambrian fauna: see [[http://www.trilobites.info/triloclass.htm the image here]] for having an idea. The large guy in the center is immediately recognisable, by far the biggest creature in this fauna: ''[[UsefulNotes/StockDinosaursNonDinosaurs Anomalocaris]]''. Of course it is the most portrayed Cambrian animal in documentaries and illustrations, classically mentioned as "[[SeaMonster the first sea monster ever appeared on Earth]]". Actually, if alive today, the "terrible" anomalocaridid would appear simply as a sort of "lobster" 3 ft long, shell-less and pincer-less... nothing dangerous for a tough-boned, tough-muscled, tough-skinned mammal we are in comparison. Apart from ''Anomalocaris'' we can mention other three invertebrates which are stock in drawings: ''[[http://en.wikipedia.org/wiki/Hallucigenia Hallucigenia]]'', ''[[http://en.wikipedia.org/wiki/Opabinia Opabinia]]'', and ''[[http://en.wikipedia.org/wiki/Pikaia Pikaia]]''. The first has a name that means "hallucination generator"; it was a sort of "worm" with long paired spikes for uncertain purpose, and long soft paired legs. The reconstruction of ''Hallucigenia'' has had an astounding ScienceMarchesOn tangle for many years: it was believed ''overturned'', with the dorsal spikes believed actually legs, and the legs pointing ''upwards'' ending with one small ''mouth'' each! Nobody knowns exactly in which phylum it has to be placed: maybe it was a Lobopod, aka a distant arthropod relative. ''Opabinia'' was related to ''Anomalocaris'', but had an even weirder look: maybe no other fossil animal resembles a fiction-related extraterrestrial thing more than ''Opabinia''. It had ''five eyes'' put in circular fashion on its head, and a pincer-like grasp at the end of a long, flexible proboscis, often mistaken for the mouth which was actually located behind the proboscis. When it was first described, many paleontologists didn't believed its describer was serious and openly laughed at it! But the most important find is the third guy, ''Pikaia'': despite its rather insignificant slug-like appearance, it is the most well-known vertebrate ancestor, a sort of prehistoric relative of our [[http://en.wikipedia.org/wiki/Lancelet lancelet]] (the closest extant vertebrate relative). This relevance has made ''Pikaia'' one of the unofficial symbols of evolution, just like the ur-amphibian ''Ichthyostega'', the ur-bird ''Archaeopteryx'' and the ur-horse ''Eohippus''. But wait... have you see these critters in TV at least once? A hard thing, even if you watched ''Series/WalkingWithMonsters''. In this RuleOfCool-filled show, the ''only real'' Cambrian invertebrate to appear is... Guess what? Well, the superpredator ''Anomalocaris'' of course! The other two invertebrate guys shown up are... a modern jellyfish and an [[AnachronismStew anachronistical phacopid trilobite]] - remember that phacopids first evolved in the Ordovician, while Cambrian trilobites looked very differently to the classic image we have when thinking about these animals. The absence of such awesome animals like ''Opabinia'' and ''Hallucigenia'' -- and still others, like the multi-tentacled ''[[http://en.wikipedia.org/wiki/Wiwaxia Wiwaxia]]'', the trilobite-like ''[[http://en.wikipedia.org/wiki/Marrella Marrella]]'', the caterpillar-looking ''[[http://en.wikipedia.org/wiki/Aysheaia Aysheaia]]'', the lobster-looking ''[[http://en.wikipedia.org/wiki/Sidneyia Sidneyia]]'', the "hairy worm" ''[[http://en.wikipedia.org/wiki/Canadia Canadia]]'', etc. -- makes another egregious example of a [[TheyWastedAPerfectlyGoodPlot missed opportunity]]. Talking about ''Pikaia'', this time it's missing is no problem for us: the aforementioned proto-vertebrate ''Haikouichthys'' did perform its role. Still another thing: if you watch the list of creatures from the Burgess Shale, you'll note almost all animals (the main exception being ''Anomalocaris'') have uncommonly short scientific names, most of them ending in '''-a'''. A rather amusing thing to read, and - let's face it - a ''true'' oasis of happiness among so many other unutterable, absurdly-difficult names.