Early Jurassic from the Dinosaur Collector

updated 040105 poof 020606

201 million years ago, about 50% of all terrestrial vertebrate families were wiped out at the end of the Triassic.  Plants also exhibit a low diversity, dominated by primitive conifers.  The new flora favored high browsing herbivores like the prosauropods.  The first large theropods appear.  The theories for the extinction include a possible meteor strike, but no conclusive evidence has been put forward.  The Late Triassic witnessed a series of extinctions that marked the change from low browsing aeteosaurs and dicynodonts preyed on by archeosaurs, to the high browsing prosauropods and large theropods. This has been used as an argument that dinosaurs out-competed the earlier forms. It also possible they were the lucky survivors of the extinction that allowed them to diversify and fill the vacant niches.

Plateosauruswas 20 - 27 feet long and normally walked on all fours, though it could stand upright to reach the leaves of trees. It had small, leaf-shaped teeth and ate plants and small animals. Both feet and hands had 5 digits, with 1 claw on the forelegs and 3 on the back legs. It had broad feet, a small, strong head, and a relatively short neck. It is one of the most commonly found dinosaurs, and in Europe fossils have been found in groups, indicating plateosaurs may have lived in a social group, though the find may also be the result of flood waters depositing individuals.

The Bullyland Plateosaurus above in the popular bipedal posture. This was the original interpretation, and the pose dates back to the Marx figures of the 60's. This figure was recently retired and repalced with a figure on all four feet.  Superficially, prosauropods look pretty much alike, so if you have a Plateosaurus in your toy series there isn't much incentive to do any other prosauropod figures. The Kayenta Formation is located in Arizona, and is one of the richest Early Jurassic formations in the Glen Canyon Group. The dinosaurs currently known from the formation are Dilophosaurus, Syntarsus, the prosauropod Massospondylus, Scutellosaurus and Scelidosaurus.  Scelidosaurus was 14 feet long and shows similarities with Stegosaurus and Ankylosaurus, with bony plates down its back and a heavy body highest at the hips. Seven rows of bony studs and spikes were set into the skin on its back.

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Use the scroll bar to view the panorama. PlayVision has produced several lines of figures left center is the AMERICAN MUSEUM OF NATURAL HISTORY Plateosaurus, left two of their Plateosaurus from their mini line.  The grey Scelidosaurus is from the Oriental Trading Company.  Directly center the three versions of Battats Dilophosaurus eyeing the Invicta Scelidosaurus.  The lime green figure in back is a recast Inpro Heterodontosaurus the dark green original is to the right. Finally the Carnegie Safari group their two Dilophosaurus figures and Plateosaurus.  

Large crested therapods from the Early Jurassic found in various parts of the world are often attributed to Dilophosaurus.  Dilophosaurus had long, powerful legs, short arms, and 2 thin, highly arched crests on its head for display. Scutellosaurus was a small plant eater about 4 feet long with small bony studs guarding the back of this early relative of Ankylosaurus and Stegosaurus. It walked on all fours but could also run on its hind legs, with a very long tail for balancing.

Dilophosaurus owes its current popularity to Jurassic Park; though the king of the Early Jurassic was a biter, not a spitter. Upper left is a Carnegie Safari Dilophosaurus, center are two versions of Battat'sDilophosaurus (the difference being the second edition had a square "snow shoe" to allow it to stand). Scutellosaurus, a possible ancestor of the later stegosaurs and ankylosaurs, is not often reproduced as a figure; in the lower left corner, biting its tail, is a copy of Panosh's figure. While the gray figure between the two Battat Dilophosaurus  is a Toys and Things version Scutellosaurus.

Prosauropods were the dominant large plant eaters of the Late Triassic and Early Jurassic. They appear to have all followed the same body plan, differing mainly in size. They seem to disappear in the Middle Jurassic for reasons not clear at this time. They are replaced world wide by the similar but larger sauropods, which they are related to, but probably not ancestral to.  Prosauropods and stegosaurs are the only major dinosaur groups to die out before the Late Cretaceous extinction.

  Massospondylus would have resembled the Carnegie Safari Plateosaurus upper left, except for being smaller.

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