Newtonsaurus

MEANING: Newton's lizard

PERIOD: Late Triassic

CONTINENT: Europe

Newtonsaurus is a basal theropod known from its lower jaw, finally named 100 years after being described by Edwin Tulley Newton in 1899. Newtonsaurus has been reclassified many times and may be a coelophysoid, though this remains uncertain. It is estimated at 5–7 meters in length, making it one of the largest theropods of the Late Triassic.

Abstract from paper: A large jaw of a predatory archosaur from the latest Triassic of South Wales, named Zanclodon cambrensis, has long intrigued vertebrate palaeontologists. Could it be the oldest large theropod dinosaur? Here we reanalyse the specimen based on a new 3D digital reconstruction. We confirm first that it is indeed latest Triassic in age, most likely extracted from sandstones of the Cotham Member of the Lilstock Formation (Penarth Group, Rhaetian). Anatomically it shows features of theropod dinosaurs rather than other large non-dinosaurian predatory archosaurs of the Triassic. It shares general characteristics with European coelophysoids of similar age such as Liliensternus and Dracoraptor but is considerably larger. It is not a megalosauroid, as suggested previously, but it is unclear whether it might be an averostran or tetanuran. Its close similarity to Dilophosaurus suggests that this left-hand mandible specimen represents a more derived basal neotheropod and we assign it to a new genus, as Newtonsaurus cambrensis.

Newtonsaurus is from the Late Triassic. The Triassic is the first geologic period of the Mesozoic, spanning from the end of the Permian Period 252 million years ago to the beginning of the Jurassic 201 million years ago. Both the start and end of the Triassic were marked by major extinction events. In the aftermath of the devastating Permian-Triassic extinction, life gradually rebounded, giving rise to new groups that would shape the Mesozoic Era. The global climate during the Triassic was mostly hot and dry, with vast deserts dominating the interior of the supercontinent Pangea. Over time, as Pangea began to rift apart, the climate slowly became more humid, creating new environments and opportunities for ecological diversification.

For much of the Triassic, dinosaurs were not yet the dominant terrestrial animals. Instead, the land was populated by a variety of other reptiles, including sprawling archosaurs. Early synapsids, the lineage that would eventually lead to mammals, were also still present but declining. Vegetation was dominated by drought-tolerant plants such as seed ferns, cycads, ginkgoes, and early conifers. These hardy plants formed the base of recovering ecosystems during this volatile time.

It wasn't until the Late Triassic, around 230 million years ago, that the first true dinosaurs appeared. Early forms were small, bipedal, and lightly built, likely preying on insects and small vertebrates. While they remained minor players compared to other reptilian groups, their agility, upright stance, and efficient breathing gave them advantages that would prove crucial in the long run. As the Triassic drew to a close, another mass extinction event reshaped life on Earth once again, wiping out many of the dominant reptile groups and clearing the way for dinosaurs to rise to prominence in the Jurassic.

Newtonsaurus is a basal theropod. Theropods are a lineage of bipedal saurischian dinosaurs that first appeared in the Late Triassic. The earliest forms were generally slender, lightly built predators with long legs, grasping hands, and serrated teeth. These basal theropods represent the first major radiation of carnivorous dinosaurs, establishing many of the anatomical traits that would define the group for the rest of the Mesozoic. Their adaptations for speed, agility, and active predation helped make them some of the most successful dinosaurs of the early Jurassic landscapes.

From these beginnings, theropods went on to diversify into a remarkable variety of forms. Later lineages produced the giant allosauroids and tyrannosaurs, as well as smaller, feathered maniraptorans including modern birds - the only theropods still alive today. While most theropods remained carnivores, some later groups evolved herbivorous or omnivorous diets, reflecting their evolutionary flexibility. Basal theropods stand at the root of this history, providing an important window into how the earliest meat-eating dinosaurs set the stage for one of the most dynamic and enduring dinosaur lineages.