Science Marches On / Prehistoric Park

• Tyrannosaurus is being shown pursuing prey with sprinting speed; this was debated at the time, but nowadays it's generally agreed upon that giant theropods like Tyrannosaurus could not run because the impact of each footfall would pulverize their legs. At best, an adult Tyrannosaurus could maybe manage a 'speed walk' stride of about 10 mph.
• The Triceratops in the show is specifically identified as Triceratops horridus, but a study in 2009 found that T. horridus only lasted up until the Mid Maastrichtian, and by the Latest Maastrichtian had evolved into T. prorsus (which primarily differed by a larger nose horn, small frill, and deeper jaw). Skin impressions since found of Triceratops also show it had relatively large body scales, including pointy scutes on its back.
• The growth rate of the Tyrannosaurus depicted (stated to double in size every year) is extraordinarily fast, with most studies since corroborating an extended period of juvenility lasting about 14 years. While the time span of the series is left ambiguous, it's certainly not as long as 14 years, and Matilda and Terrance should not have been even close to the size shown by the last episode.
• While not explicitly stated, Matilda being much bigger and more aggressive than Terrance is probably a nod to the hypothesis that female tyrannosaurs were larger than males. However, the evidence once used to support this idea has since been discredited (while it could still be possible, it would be purely speculative now, as there is no confirmed sexual dimorphism for the species; it's equally possible males were bigger or that they were the same size).
• The show's depiction of Crassigyrinus scoticus was based on a 1985 reconstruction of the animal, which gave it a tall, vaguely tadpole-like head based on a crushed skull. But a 2023 redescription, using digital reconstructions derived from CT scans, determined that its skull was broader and flatter, more in line with most other amphibious Carboniferous stem-tetrapods.
• The notion that Deinosuchus could reach 50 feet has been debunked and was already heavily scrutinized at the time the show aired. All known specimens are estimated to have reached between 26 to 35 feet, while some exceptionally large but fragmentary specimens might have grown as big as 36-40 feet but even that is controversial. And the claim that it was the "largest crocodile to have ever lived" is dubious, since, if nothing else, it had a number of competitors for that title, such as the Miocene-aged Purussaurus and Rhamphosuchus, and the Early Cretaceous Sarcosuchus, who itself was later downsized from 40 feet to a smaller but still quite imposing 30-32 feet.
• The basal troodont Mei long is depicted as man-sized in the show, since the holotype and paratype were initially interpreted as juveniles due to their large eyes and tiny size, but later studies showed that they were likely fully-grown animals (or at least close to adulthood). Though humorously enough, only one year after the show aired, we described a different coelurosaur from Liaoning that fits the profile of the show’s Mei long much better; the wolf-sized compsognathid Sinocalliopteryx gigas.
• The sauropods Nigel brings from Early Cretaceous China are only referred to as titanosaurs, since no known sauropod material from the Yixian Formation in Liaoning was properly named at the time. Now we have three taxa known from the region; Dongbeititan, Ruixinia, and Liaoningotitan. Furthermore, their appearance in “Dino Birds” is treated as something of a surprise, as Nigel wasn’t expecting to find large animals in this habitat. We now know that large dinosaurs likely weren’t an unusual sight at Yixian, as besides the aforementioned sauropods, there was also the mid-sized iguanodont Bolong and the feathered, 30-foot tyrannosaur Yutyrannus.
• Bob pacifying the titanosaurs by feeding them gastroliths probably wouldn't work in reality, as subsequent studies suggest that ingestion of stones by sauropods is largely if not purely accidental, unlike other dinosaurs, since they don't match the morphology or occur in the quantities of true gastroliths. Sauropods likely did not require stones to digest vegetation.
• Ornithomimus were not duck-like filter-feeders "more similar to Daffy Duck than emus" as portrayed in the program. This theory was made in the middle 2000's from the putative discover of a sort of "lamellae" on the horny beak of some ornithomimosaurs, similar to those seen in duck and flamingos (both filter-feeders). This theory become quite popular at the time among paleo-fans, and the show, incidentally, was produced just in those years: hence the duck-feeding thing seen in the program. But just a few years later, this hypothesis has been discarded: those lamellae are arguably simple "wrinkles" on the beak like those seen in other non-filter feeding birds. Anyway, the rest of Ornithomimus's anatomy doesn't show any specialization for a flamingo way-of-life. It was more like modern running birds: ostriches, rheas and emus. It's also known now that Ornithomimus was covered in feathers not just as chicks but as adults, with several specimens preserving plumage impressions showing they even had ratite-like wings.
• There's an ongoing debate on just how Microraptor "flew" (if at all), with some later studies suggesting it could have actively flown rather than glided, and was the wrong color in the show.
• Microraptor is depicted as an insectivore but stomach content from multiple individuals has subsequently revealed that it was a versatile predator who preyed on mammals, lizards, fish, and even flying birds. It might have been small but it was no less of a skilled hunter than its larger cousins like Velociraptor and Deinonychus, the same way a house cat is effectively a miniature tiger.
  • Microraptor would not have been a contemporary of Yixian fauna such as Mei long and Incisivosaurus, as it instead comes from the overlying Jiufotang Formation, making it younger by around 3-5 million years. That said, it had several close relatives who were part of the Yixian biome, such as Sinornithosaurus, Zhongjianosaurus, and the relatively large (by microraptorian standards) Changyuraptor.
  • The unnamed pterosaurs in the Yixian Formation and the Nyctosaurus are both shown hunting by skim feeding. This was a widely proposed hypothesis for how piscivorous pterosaurs fed, but it has few adherents today because there was never any real evidence for it and plenty of evidence against it (among modern fishing fliers, only the aptly named and highly specialized skimmer birds hunt this way).
• Young Triceratops did not look like miniature versions of the adults. The youngest individuals had little stubs for horns and a scalloped frill, while the horns pointed upwards in subadults and the spines lining the rim of the frill are much spikier. Forward-pointing horns and smooth frill edges only appeared in the adults.
• Early Cretaceous China likely had a more temperate climate than originally thought and might have even experienced snowfall! There must have been a reason its apex predator, the 30-foot Yutyrannus, had a full-body coat of thick proto-feathers.
• The show claims Elasmotherium died out 150,000 years ago. New evidence suggests that it actually survived as recently as 50,000 years ago. Adding to this, some have suggested that instead of a massive horn, it might have sported a small bump containing a resonating chamber similar to the crests of hadrosaurs (no direct evidence of a horn is known, so its shape is speculative), but that remains controversial.
• Toxodon is depicted as an amphibious animal akin to modern-day hippos (with Nigel directly comparing the two). However, later examinations of the proportions of its femur and tibia, as well as the position of its head, below the top of the spinal column, showed that it was ill-suited for an amphibious lifestyle, as well as the fact that Toxodon fossils are usually found in arid to semi-arid grassland biomes, both of which suggest that it was more analogous to a rhino than a hippo.
• It’s unlikely that terror birds were outcompeted by saber-toothed cats since, for one, the last of the giant phorusracids, Titanis walleri, actually migrated into North America and coexisted with saber-toothed cats and a whole slew of other mammalian predators such as wolves, running hyenas and short-faced bears for nearly 3 million years and secondly, we don’t actually have any evidence that saber-toothed cats and phorusracids ever overlapped in South America, as the oldest known Smilodon fossils from the continent (circa 1.8-1.5 mya), come after the extinction of the local terror birds. And the same is true for most other placental carnivores from the north, who only arrived in South America long after the terror birds vanished from the fossil record. Some phorusracid fossils from Uruguay might come from the Middle to Late Pleistocene, but their age is controversial, and even then, they are very small forms, weighing a mere 5 kg, while the last of the giants vanished 2 million years ago.
• Beginning in 2011, about five years after the series aired, Troodon was found to be a collection of several distinct genuses and split into a number of new taxa — and, due to the genus' convoluted discovery history, the only "true" Troodon remains left were a small number of teeth, leading to most paleontologists no longer considering it a valid genus. The dinosaurs seen here would most likely be considered Stenonychosaurus (which had been previously synonymized with Troodon in the 1980s) today.
• "Super Croc" features Albertosaurus and Stenonychosaurus (referred to as Troodon) living in Texas. The episode is nominally based on the Aguja Formation, which has troodontid teeth that were previously lumped into Troodon but probably represent a different taxon (or could even belong to pachycephalosaurs). The inclusion of Albertosaurus was likely based on a still-undescribed gracile tyrannosaur from Aguja, but also on another gracile specimen from Alabama which famously has bite marks attributed to Deinosuchus, with both animals having tentatively been likened to Albertosaurus in the past, but the former has since been found to represent a different tyrannosaurid (likely not an albertosaurine), while the latter was named and described as Appalachiosaurus (a non-tyrannosaurid tyrannosaur unique to Appalachia), thus leaving Albertosaurus and Stenonychosaurus restricted to Montana and Alberta. Parasaurolophus, on the other hand, was more widely distributed and although not known from Texas, it has been found in the neighboring state of New Mexico.
• In "T. rex Returns", we briefly see a flock of Nyctosaurus soaring around at the time of the K-Pg extinction. This might have been based on "Nyctosaurus" lamegoi, a larger Maastrichtian species known from a partial humerus from Brazil, which was previously cited as evidence that the genus survived until the very end of the Cretaceous, but subsequent studies have found it to more likely be a distinct genus and more closely related to Barbaridactylus (named in 2018), another large Maastrichtian nyctosaurid (though it comes from Morocco).