Jurassic Park Period Part 6

 Fauna - Amphibians & Land Animals

Amphibians - The Early Jurassic Prosalirus is thought to represent the first frog relative capable of hopping like living frogs. Recognizable frogs like the South American Notobatrachus are known from the middle of the Jurassic. Although salamander-like amphibians are known from the Triassic, salamander ancestors first appeared during the Jurassic.

But most of the land animals mentioned were dinosaurs. Dinosaurs had morphologically diversified in the Late Triassic, but experienced a major increase in diversity and abundance during the Early Jurassic after the extinction of other reptile groups, becoming the dominant vertebrates in terrestrial ecosystems.

Theropods - Theropods are a group of dinosaurs that had hollow bones and 3 claws on each appendage. They first appeared in the Late Triassic. One group, called the Neotheropoda, persisted into the Early Jurassic. The earliest 'bird snout' members of the averostrans appear during the Early Jurassic and continue throughout the rest of that period and the Jurassic. Most theropods were carnivorous, although the unusual Limusaurus of China had a herbivorous diet, with adults having beaked jaws, making it the earliest known theropod to have converted from an ancestrally carnivorous diet. The Coelurosaurs first appeared during the Middle Jurassic, including early tyrannosaurs such as Proceratosaurus. The scansoriopterygids was a group of small feathered coelurosaurs with membraneous, bat-like wings for gliding, and records have been found from the Middle to Late Jurassic.

Ornithischians - This refers to an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. Hence they were called "bird-hipped", or Ornithischia. However, birds are only distantly related to this group, as birds belong to the theropod line of dinosaurs. The Ornithischians included those known as "horn-faced", such as Triceratops, and the armored dinosaurs such as stegosaurs and ankylosaurs. There is strong evidence that certain groups of ornithischians lived in herds, possibly segregated by age. Some were at least partially covered in hair- or feather-like pelts, and there is much debate of whether these pelts may have been primitive feathers.

The earliest definitive ornithischians appear during the Early Jurassic. The earliest Ankylosauria and Stegosauria appear during the Middle Jurassic. At least some ornithischians were covered in protofeathers.

Sauropodomorphs - Sauropods are a group of "lizard-hipped" dinosaurs. They had long necks and tails, small heads and 4 huge, pillar-like legs. They became the dominant large herbivores in terrestrial ecosystems during the Jurassic. Some reached gigantic sizes, becoming the largest organisms to have ever lived on land. Bipedal sauropodomorphs continued to exist into the Early Jurassic, but went extinct by the beginning of the Middle Jurassic. Quadrupedal sauropomorphs were a hold-over from the Late Triassic. One type of quadrupedal from the earliest Jurassic of South Africa reached an estimated weight of 12 tons, far in excess of other known sauropodomorphs.

So it appears there were lots and lots of dinosaurs ambling across the landscape. I know I earlier said we would pause to look at some of the better-known dinosaurs, but I didn't realize how many episodes the Jurassic Period would take, just to give it this brief look. So I've changed my mind, and the next episode (all the rest of the fauna) will finish up the Jurassic Period before I go on to the next time period in the history of the Earth. Later on, when I've finished the Earth's prehistory, I'll find a time to take a look at various species of dinosaurs, so keep watching, because I'll get to them!