The Real Jurassic Park

The central US about 150 million years ago. The closing years of the Jurassic as it would come to an end at 145 million years ago with a whisper. Previous boundaries for time periods are often marked by catastrophic events heralding mass extinctions. The Jurassic to the Cretaceous does not. One could note that evolution kept on path as Jurassic dinosaurs continued to diversify and derive into the great varieties of the Cretaceous. Even bigger sauropods, massive predators, more feathers and small dinosaurs with ferocious appetites and attitudes.

This image can be synonymous with Wyoming. The sea reached deep into the continent with a massive bay, but was still several hundred miles from here where and low rocky hills and small mountains were inland. This region was seasonal with dry and wet periods. This is the season of drying. Rivers recede leaving fertile fields where ferns and other plants pop up near cycads and ginkgoes and conifers. The ginkgoes are even taking over from the conifers in this low altitude region. Calamite horsetails line the shores, but will disappear as the rivers dry and be replaced by meadow horsetails and eventually only plants that can handle desert conditions.

For now a herd of Apatosaurs migrate into this valley attracted by the still lush vegetation and running river, leaving behind the drier uplands. Apatosaurus is related to Diplodocus and is from the family Diplodocid. They are characterized by forward held necks and long whip like tails. They are thought to be grazers/browsers of ferns and low bushes, sort of the lawnmowers of the Jurassic. They averaged about 70 feet long. It is speculated that they used their whip like tails for defense and to “crack it” like a whip to produce identifying sounds to other members of the herd for warnings or some form of communication.

There is a story of a Brontosaurus, a dinosaur many of us heard of as kids. This brontosaurus has a checkered past. Originally discovered by O.C. Marsh in 1879 a fairly complete skeleton was found, but it was missing the skull, some tail bones, feet and some leg bones. He named it Brontosaurus, but 25 years later it was put back in with the Apatosaurs by Elmer Riggs. Despite that and despite missing a skull, restorations were created displaying an animal with its neck raised to high, its tail too short and a skull more like the unrelated sauropod Camarasaurus and museums named it...Brontosaurus. Though improvements were made on the original design over the years, including making the skull smaller and more like Diplodocus, it really wasn't until 2015 that a group of paleontologists found enough differences between Brontosaurus and Apatosaurus to put Brontosaurus as a subfamily and with three different species as well. Some scientists are still not convinced that it deserves the sub classification, but for now the scientific community is standing by the new finds.

Another sauropod visible is Brachiosaurus. They are much less common in the fossil record, but they are present. Water, sediments and silt are required for fossilization, so perhaps these dinosaurs did not spend as much time around larger bodies of water. They were huge and are among the largest land animals known. They were at least 85 feet long from nose to tail, but they were stocky and robust as well with long forelegs and a tall high reaching neck that could reach up to 35 feet. Where Diplodocids fed off the low plants, Brachiosaurus fed from taller trees including ginkgoes and conifers. The bony crest atop their head is thought to have supported a fleshy crest that air could be blown through to “hoot” or “honk” to others of its kind for species recognition and communication.

The other herbivore to be seen in this image is Stegosaurus. There are a few species of Stegosaurus with back plates of different size, shape and configuration. And the species vary in size from the more typical 25 feet long to ones that were 30-35 feet long. All had the back plates and the signature spiked tail and fed on plants. The tail spikes are an obvious defense weapon, but the plates are considered more for display as they are too delicate to form any kind of real defense.

The small pterosaur is a speculative anurognathidae, possibly Messadactylus. The anurognathids had short skulls, very short tails and it appears the wing webbing attached just above the feet. This one here has a wingspan of about 6 feet and likely fed on small mammals and reptiles.

Finally the quiet observer is Torvosaurus. One of the largest if not the largest predator of the late Jurassic world. The only thing bigger would have been Saurophaganax or an aberrant Allosaurus. Torvosaurus is currently classified with Megalosaurid family. They averaged 33 feet in length, had long snouts and a mouth full of flesh shearing teeth. There are species known in the Morrison Formation of the US and from remains in Portugal.

Before the Atlantic truly began to widen in the late Jurassic and early Cretaceous, land bridges would appear between North American and the European archipelagos allowing species to migrate from North America to as far as Africa and Asia and likely vice versa. As long as the environment was similar the species would evolve in similar fashion as those from where they originated.

This could explain the relationships of the earliest Tyrannosauridae in Asia and how the later T. Rex and his relations ended up in North America, while very similar species like Tarbosaurus were in ancient China. The same could be said of Megalosaurids in England and ones in North America and Allosaurids forming new families like the Carcharodontisaurids in Africa and later in South America via African and South American land bridges. It has to be remembered that species in the prehistoric world lived for millions of years changing very little, which gave them ample time to spread around the globe where ever land connected different continents together.

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