Plateosaurus engelhardti, P. gracilis
Name: Plateosaurus engelhardti, P. gracilis
Name Meaning: Broad Lizard
First Described: 1837
Described By: von Meyer
Classification: Dinosauria, Saurischia, Eusaurischia, Sauorpodmorpha, Plateosauria, Plateosauridae
Plateosaurus is, arguably, the most famous saurpodomoprh (”prosauropod”), and is typically used as an example of what early members of the group looked like. It lived from about 214 to 204 million years ago, in the Norian to Rhaetian ages of the Late Triassic. It is known from multiple individuals, many of which are well preserved, and across a variety of age ranges. As such, it has been found in many sites across Europe. The original was found in Heroldsberg, near Nuremberg, Germany. It has also been found along the Neckar and Pegnitz river valleys, in Switzerland, and in France. Three localities especially yielded large numbers of specimens in good quality: near Halberstadt in Saxony-Anhalt, Germany; Trossingen in Baden-Württemberg, Germany; and Frick. It was also found in the Fleming Fjord Formation in Greenland, as well as from the Snorre Oil Field in the North Sea, making Plateosaurus the first dinosaur found in Norway.
Plateosaurus was one of the larger “prosauropods” (which is an antiquated term that typically applies to those saurpodomorphs that are not sauropods, however, that is not really an accurate term cladistically, but it still holds meaning to dinosaur enthusiasts, so… I use it?), ranging between 5 and 10 meters long, but the genus was actually very variable when it came to the size of adults. Its growth was initially rapid, continuing slowly beyond maturity, but it would stop growing once it reached a maximum size (around 10 meters long). However, this did really depend on the individual - some individuals were found to be fully grown at only 4.8 meters long. The rapid growth involved suggests that it may have been endothermic, or at least on the way to developing endothermy. It also had avian-style lungs, which further indicates that endothermy may have been present in this genus. The presence of avian-style lungs in a dinosaur that is not in the line that includes birds indicates that avian-style lungs may have been an ancestral trait for all of the saurischians, or even Dinosauria. This could, furthermore, indicate that all dinosaurs were in fact endothermic. Some individuals were fully grown at 12 years, other still grew slowly at 20 years, and others were still growing rapidly at 18. The oldest individual found at 27 was still growing.
Source: sheriff-kyle, who drew this especially for ADAD! Thanks Kyle! Check them out!
It was obligately bipedal - so any reconstructions with it walking on all four are less than correct. This is not an uncommon phenomenon, however; every imaginable posture has been imagined for this animal. Two early investigators were at odds with one another: Von Huene assumed that it was bipedal and digitigrade (meaning, walked on its toes, like birds and theropods). Jaekel, on the other hand, though it was quadrupedal, with a sprawling limb position like lizards. Then, Jaekel changed this tune to clumsy, kangaroo-like hopping… which is… interesting… to picture… Starting in 1980, better understandings of dinosaurian biomechanics allowed for better understanding of its posture: the new interpretation was digitigrade, and a horizontal back, though it was still thought that it could be either bipedal or quadrupedal (for rapid and slow locomotion respectively). The tail was straight, which would allow for bipedal posture. However, detailed study of the forelimbs by Bonnan and Senter demonstrated that they could not be pronated (something, I would remind everyone, this dinosaur has in common with theropods, including raptors, aka animals that could not bend their wrists so their palms were facing their torsos). This would make it an obligate biped, which is further emphasized by how much longer the hind limbs were than the front limbs.
Source: lythronax-argestes-the-gore-king, my friend! Check him out too!
It had a small and narrow skull, rectangular in shape, and it had thick, leaf-shaped, serrated teeth, suitable for crushing plant material, indicating that Plateosaurus was herbivorous (rather than omnivorous, like earlier sauropodmorphs). It had a low jaw position, giving the chewing muscles great leverage, so it also had a powerful bite. It had eyes on the sides of its head, allowing it to have a wide field of vision to look for predators; it also had sclerotic rings, or bon plates that protected the eye. It’s large field of vision, however, came at a cost - it did not have binocular vision, and thus, poor depth perception. No juveniles or hatchlings are known for the genus, so it is unknown how the body changed during the initial 10 years of rapid growth. It has often been found alongside the shed teeth of theropods, indicating that it may have been hunted upon by them, or at least scavenged on (given its large size, and the relatively small sizes of early theropods).
Source: thewoodparable (y’all know his work by now let’s be real)
No gastroliths have ever been found in association with Plateosaurus, which contradicts the idea that all large dinosaurs would swallow gizzard stones to digest food. The use of gastroliths for digestion developed from basal theropods to birds, with similar development in other species like Psittacosaurus. Comparing the scleral rings of Plateosaurus and modern birds has lead to the understanding that it may have been cathemeral, active throughout the day and night, though it may have avoided critical times during the day such as mid-day heat. Though it has never been found in association with them, given the ancestral character of protofeathers in Dinosauria, and its relatively small size and basal position compared to such sauropodomorphs as the titanosaurs (which were decidedly scaly), it is reasonable to suppose that Plateosaurus, like all basal sauropodomorphs, was covered in a coat of protofeathers. It is not clear whether or not it lived in herds, with no clear evidence either way. It may have travelled in loose herds, or congregated together based on food availability.
Plateosaurus was one of the main herbivores present in Europe at the end of the Triassic, and was probably a commonly targeted prey species by large reptiles and even larger theropod dinosaurs. Herrerasaurus, though living in South America, did reach a size that could have allowed it to threaten animals like Plateosaurus, and given that South America and Europe were linked in the supercontinent Pangaea, it is possible that it did. There are two valid species of the genus: P. gracilis and P. engelhardti, the latter being the first described, though it is possible that there are more, given that the original find of P. gracilis has no skulls, and other assigned specimens have skulls and skeletal material that don’t overlap enough with the original to ensure that they’re all in the same group. P. gracilis was the older species, in the early Norian; whereas P. engelhardti was from the later Norian. This was a successful genus, with a wide range of habitats and a long time span of existence, and it is no wonder that it is one of our best known members of the early sauropodmoprh group.
Shout out goes to kummakat!