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Useful Notes / Prehistoric Life - Hadrosaurs

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The hadrosaurs commonly shown in media are usually North-American. Other than the four most known kinds (Parasaurolophus, Edmontosaurus, Corythosaurus, and Maiasaura), other "duck-billed dinosaurs" that have been quite common are: Hadrosaurus (the official but fragmentary prototype of the family), Kritosaurus (whose portrayals actually are based upon another relative, Gryposaurus), Saurolophus (often confused but not-related with Parasaurolophus), and Lambeosaurus (this one may get confused with Corythosaurus). All them have even made occasional apparitions in films, novels, and TV programs. Since the 1990s Hypacrosaurus has also began to show up with a certain frequence. Among Asian kinds the gigantic Shantungosaurus, the "unicorn" Tsintaosaurus, and the primitive Bactrosaurus (not a true hadrosaur yet according to recent researches) are perhaps those most portrayed, together with the Asian species of Saurolophus.


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    North & South American Hadrosaurs 

Bone-Wars Duckbills: Claosaurus

  • After Leidy described Hadrosaurus in 1858 as a generic Iguanodon-like animal, then Edward Cope and Othniel Marsh described for the first time hadrosaurians as “duck”-headed dinosaurs in the following 1870s/1880s. Cope described the popular “Trachodon copei” (and also the enigmatic Pteropelyx and the teeth of "Cionodon" and "Diclonius"); Marsh a much more obscure animal than the "trachodont": Claosaurus agilis, a fragmentary animal which is worth of note both because was one third long than most other hadrosaurs, and because is was traditionally believed the most primitive North American duckbill. After its description, Claosaurus agilis ("agile broken lizard", because of its incompleteness and its slenderness) was involved in the incredible "Trachodon"/Anatosaurus/Edmontosaurus/"Anatotitan" taxonomic tangle, and today is often regarded as a close hadrosaur-ancestor but still not a proper hadrosaur.

The Lophus Family: Brachylophosaurus & Prosaurolophus

  • “Loph-” is a common particle among hadrosaurian names (and theropodian as well: think about “Dilophosaurus”…); this is indeed the Greek for crest. Other than Saurolophus and Parasaurolophus, there is also a third similarly-named hadrosaur, Prosaurolophus, which means “before Saurolophus” (and was probably related with it). Another is Brachylophosaurus (“short crested lizard”, maybe closer to Maiasaura), and still another is the small Lophorhothon ("crested nose"). note  The first two examples are small, primitive North American true hadrosaurs found some years after Saurolophus but with incospicuous crests similarly to Maiasaura. In spite of having left abundant remains, their comparatively modest appearance make Prosaurolophus & Brachylophosaurus rare sights in media — even though Brachylophosaurus has recently given us some spectacular fossils which might make it more widely-known: among these, a true “mummy”, just like Edmontosaurus. Some scientists have hypothized that Brachylophosaurus and Maiasaura used their thickened cranial crest for headbutting their rivals, a bit like what has traditionally been said about pachycephalosaurians: like the latter, this hyp is not demonstrated — even though some hadrosaurian ribs fractured and then hailed could be a possible proof of this behavior.

Corythosaurus' Cousin: Hypacrosaurus

  • If you see a “frisbee”-crested hadrosaur in books or documentaries, don't assume it’s Corythosaurus. The latter had indeed a "twin" called Hypacrosaurus altispinus, with a similar crest though fairly-smaller. Sadly, since some (possibly female) Corythosaurus also have a rather low crest, this doesn’t help us so much to separate the two; the most sure trait to do it is to watch the taller neural spines of Hypacrosaurus in a mount (altispinus means "tall-spined"). Not surprisingly, Hypacrosaurus has been confused with Corythosaurus or even Lambeosaurus in the past, and to complicate matters, some juvenile remains from these three animals were even labeled as two genuses on their own, "Cheneosaurus" and "Procheneosaurus"! Hypacrosaurus was, notably, the last of the crested duckbills to live in North America, with its most recent fossils dating back to 67 million years ago. In other words, it may have coexisted with T. rex, Triceratops, and other Stock Dinosaurs from that time, though there is presently no fossil evidence of this. If it was so, this would make the pop-portrayal of T.rexes hunting Corythosauruses more realistic. In the nineties, a nidification site in North America full of Hypacrosaurus nests and hatchlings has been discovered, analogue to the classic Maiasaura; this find has made Hypacrosaurus a more well-known duckbill.

North and South America: Secernosaurus

  • Most hadrosaurs have been described in Alberta at the beginning of the XX century, in the second memorable “Dino-Rush” led in North-America. Among them, other than Parasaurolophus, Corythosaurus, Saurolophus, and Kritosaurus, there's one that has traditionally been ignored for decades by media: Gryposaurus notabilis ("noble hooked lizard"; not "noble griffin lizard" as usually said). Found in 1910, it owes its name from its hump-like nose: but its bumped skull was before the 1990s mostly attributed to the genus Kritosaurus. After that date, it was confirmed that the skull belonged to it instead. Other two new discovered hadrosaurs in western USA also show bumped heads, the Native American-sounding Anasazisaurus and Naashoibitosaurus, both known from only their skulls. Some “Kritosaurus” remains have been described in South America, but they almost certainly belong to the only surely-valid South American hadrosaur: Secernosaurus ("separated lizard"), a small primitive duckbill which is likely a migrant of North American origins. This one could have been one of the favorite preys for the famous bull-horned Carnotaurus, and has been portrayed as such in illustrations. From North America come other two very recent and interesting discoveries: Angulomastacator (lit. "angular chewer") with its curious jaws curving below, maybe to better take vegetation on the ground; and Velafrons (lit. "sail front") which looks rather like the Asian Olorotitan.

    Asian & European Hadrosaurs 

Manchurian Dinosaur: Mandschurosaurus

  • Everywhere seems to have started with a large ornithopod. We have Hadrosaurus in the USA, Iguanodon in Europe; and what about China? Here, the role was assumed by a little-known hadrosaur, Mandschurosaurus - “Mandschuria” is the German graphy for Manchuria, the northern Chinese region where the find was made in 1930. This is not a mere case however: remember ornithopods were the “antelopes” of their time... and we know well antelopes are the most numerous large mammals in Africa.Then, several others followed: the most debated has been Tsintaosaurus spinorhinus ("spine-nosed lizard from Tsing-tao", the capital city of Shandong).

Unicorn?: Tsintaosaurus

  • Nicknamed the “unicorn dinosaur” because of its high, narrow, pointed crest on its head, Tsintaosaurus was found in the 1940s like the sauropod Mamenchisaurus, and thus is one of the “classic” Chinese dinosaurs. Few other dinosaurs have had such a tormented Science Marches On stories than Tsintaosaurus. Initially was described from fragmentary remains that seemed to show that horn-thing upon its head; then, scientists took it away in the 1990s, thinking it actually was a misplaced piece from the rest of its skull; a later find showed Tsintaosaurus really did deserve the “unicorn” title...until a 2013 study proved the "horn" was just a fragmentary backwards-pointing crest, a bit looking like that of the equally Asian relative Olorotitan but more elongated. This shows the Tsintaosaurus being a lambeosaurine, albeit of uncertain affinities. In the middle 1990s, some even hypothized that Tsintaosaurus was an invalid genus largely based upon another less-known Asian duckbill, Tanius (already found before Tsintaosaurus, but now regarded as incomplete). In the 1980s John Sibbick showed in one portrayal the tsintaosaur having a pair of small speculative airsacs at the base of its alleged upward-pointing crest like Saurolophus or the edmontosaurine duckbills.

The Giant of the Far East: Shantungosaurus

  • Discovered in the 1970s, Shantungosaurus giganteus ("gigantic Shandong's lizard", from the Chinese province it was first found) was a crestless hadrosaur quite similar to Edmontosaurus, and usually believed closely related with it. But was bigger than the latter, with the same size of the aforementioned "giant lambeosaur" Magnapaulia (15 m/50 ft long and 12 tons or more in weight); it was even bigger than some titanosaurian sauropods of the same fauna, and too big to be attacked by a Tarbosaurus; and yet Shantungosaurus has traditionally not received so much attention, even in books. Both subfamilies of duckbills, the crestless/small-crested and the large-hollow-crested one, have members both in Asia and in North-America — giving another proof about the connection between the two landmasses in Late Cretaceous by the today-Bering Strait. Recently discovered incomplete Shantungosaurus remains seem to show an even larger animal (16 m); these specimens were initially thought to be their own genera, "Zhuchengosaurus" and "Huaxiaosaurus".

Russian Guys: Jaxartosaurus & Nipponosaurus

  • Some flat-crested hadrosaurs are known from Asia: Barsboldia (named after Mongolian scientist Rinchen Barsbold), Jaxartosaurus (from the Jaxartes river in Central Asia) and Nipponosaurus ("Japanese lizard"), the latest two being found in the ex Soviet Union — the formerly-largest country in the world has surprisingly left very few dinosaurs, many of them are hadrosaurs. In the 1990s-2000s, two brand new crested hadrosaurs were found near the Amur river which divides Russia from China: the meaningfully-named Amurosaurus and the spectacular hatchet-crested Olorotitan ("titanic swan": a clear reference to Anatotitan the "titanic duck").

Borderline Dinosaurs: Olorotitan & Amurosaurus

  • Olorotitan ("titanic swan") is one of those hadrosaurs found in the border between Russia and China - near the Amur River - in the late 1990/2000s. It revealed a totally new kind of crest, reminescent of an upright axe pointing backwards: similar-looking appendages was later found in other dinosaurs of the Hadrosauridae, for example the north-american Velafrons ("sail-front") and, very recently, even in the classic allegedly "unicorn duckbill" Tsintaosaurus.

Parasaurolophus of Asia: Charonosaurus

  • If you see a “trumpet”-crested hadrosaur in books or documentaries, be sure it’s a Parasaurolophus… unless you’re watching a work made after year 2000. Indeed, in that year a very Parasaurolophus-like hadrosaur was discovered in the same Amur site cited above: Charonosaurus ("Charon lizard"). This one was also bigger than its North-American cousin… only, its skull is incomplete, with only the base of the crest preserved; the shape of the remaining crest is only a guess. Nonetheless, the discover of the “Amur hadrosaurs” has enhanced our knowledge of duckbills in general. Before that, the Asian were considered generally more primitive than the North-American ones. As we know their Asian counterparts, this is not true anymore. Among the latter, also described in the 2000s were the Saurolophus-like Kerberosaurus, Sahaliyania, and Wulagasaurus. A very primitive hadrosaur or hadrosauroid from China is Gilmoreosaurus, which was smaller and slimmer than most hadrosaurs - recalling the North American Claosaurus. Other more fragmentary Asian hadrosaurs include Arstanosaurus (once often confused with a ceratopsian) and Microhadrosaurus, lit. "small Hadrosaurus": once believed the smallest duckbill, but today it's known its fossils are juveniles.

Hadrosaurs or Iguanodonts?: Bactrosaurus & Probactrosaurus

  • Some other Asian hadrosaurs were much more generically-looking than Tsintaosaurus: for example, Bactrosaurus ("lizard from Bactria", an ancient Central Asian region), one of the smallest hadrosaurs known – only 6 m long. Discovered in China and in Russia, Bactrosaurus is traditionally regarded as one of the earliest hadrosaurs, without any crest on its head, and still rather Iguanodon-like in look – remember hadrosaurs are just very specialized iguanodontians phylogenetically speaking. But recent research has re-classified it outside Hadrosaurids proper. The bactrosaur's legacy with Iguanodon is confirmed by Probactrosaurus, an Early Cretaceous ornithopod which, like Bactrosaurus was still not a proper hadrosaur, but was going to become such. Also Asian, it was so similar-looking to Bactrosaurus to have given in The '70s a concrete clue about hadrosaurs’ ancestry (its name just means “before Bactrosaurus").

Ancient Mediterraneans: Telmatosaurus & Tethyshadros

  • While most Asian dinosaurs are known from China and/or Mongolia, several duckbills or pre-duckbills were found in unusual countries such as the former USSR, ex. Bactrosaurus, Jaxartosaurus, and Aralosaurus (found next to the drying Aral Sea), and even in Japan (Nipponosaurus) note . But there are also few hadrosaurs that have been found in Europe: the traditionally most-known is Telmatosaurus; another more fragmentary is Orthomerus. A smallish animal known from incomplete fossils, Telmatosaurus ("marsh-living lizard") is one of the several dinosaurs discovered in Late-Cretaceous Central Europe from France to Romania, along with Struthiosaurus, Magyarosaurus, Rhabdodon, and the primitive flightless bird Balaur bondoc. At the time most Europe was covered by the ancient inner-ocean Tethys (considered the ancestor of the Mediterranean, Black, and Caspian Seas), and small islands were the only pieces of dryland Telmatosaurus could have lived on. How it was able to reach these islands from Asia is still a mystery. In year 2009 its relative Tethyshadros insularis ("island-dwelling hadrosaur from Tethys") was found in Northern Italy; this is now the most complete European duckbill. Recent research, however, put even these two dinosaurs slightly outside the Hadrosaur crown group. Other two recently found duckbills in Spain, Koutalisaurus and Pararhabdodon, seem real hadrosaurs, maybe related with Tsintaosaurus.


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