Wednesday, June 13, 2018

Colobops Noviportensis: A Triassic reptile from Connecticut with a powerful bite

My reconstruction of Colobops noviportensis, inspired by the Satanic Leaf-Tailed Gecko, Uroplatus phantasticus. And yes, that IS one of those "Silkhenge" spider egg structures (first discovered in the Amazon back in 2014) in the lower left.

Here's an article I wrote for the Spring issue of Tracks and Trails, the Dinosaur State Park newsletter.

The Triassic was a time of evolutionary experimentation. In the wake of the mass extinction at the end of the Permian that killed 90% of life on Earth, only a few unspecialized species remained.  As animals adapted to the vacant ecological niches, they evolved a staggering variety of unusual forms: vacuum cleaner-faced aquatic herbivores, fan-winged gliders, long-necked “living fishing poles” and many more. The Triassic creatures probably most familiar to Dinosaur State Park’s visitors are the crocodile-like phytosaurs and the giant flat-bodied amphibian metoposaurs. But these are only the most visible members of the strange Triassic fauna. The largest and flashiest creatures. Like our modern ecosystems, there was much more diversity on the small scale lurking in the low scrub along the river’s edge, scampering among the pine branches, burrowed under roots and in the mud. Case in point, the palm-sized Triassic lizard Colobops noviportensis which had a bite unique among reptiles both living and extinct.

Colobops- whose name means “shortened face” because of its small snout-  is known from a single mostly complete skull about 2.5 centimeters long found in a sandstone outcrop near Meriden, Connecticut. Initially discovered during roadwork in 1965, the fossil was not examined scientifically until 1993. At first, it was thought to be a distant relative of the New Zealand tuatara, but a re-examination this year made with a computer-generated 3-D scan of the skull placed it in the archosauromorpha, the group that eventually led to dinosaurs, birds, and crocodiles. Furthermore, Colobops is also thought to be one of the earliest members of the rhynchosaurs, an odd group of beaked herbivorous reptiles- though Colobops itself did not show signs of having had a beak.
The major features that make Colobops unique are its large jaw muscles called adductors. Though the muscles themselves have not fossilized, their size and strength can be inferred from the exaggerated size of the temporal fossae- the holes on the back of the skull behind the eyes that accommodated them (in humans, the temporal fossae are the depressions on the sides of the skull that run from the temples down under the cheekbones). Colobops’ adductors are, relative to its skull size, proportionately larger than those of any other known reptile, prehistoric or modern. This means that Colobops had- again relative to its size- a more powerful bite than any other Triassic reptile.
Another unusual feature of this creature is the tip of its snout which is reinforced with partially-overlapping nasal bones, a trait it shares with its larger rhynchosaur cousins. This toughened nose is also similar to the snout of the unrelated modern-day amphisbaena or legless lizard and thus may indicate some level of digging behavior in Colobops or at least an adaptation to frequent blunt force to the tip of its skull.

Since no teeth were preserved in the fossil, it’s not known exactly what Colobops ate. However, its unusual jaw adaptations suggest that it had a specialized diet rather than the generalist feeding habits of many modern small lizards. Perhaps it ate tough-shelled burrowing invertebrates. Or, if it was herbivorous like its larger rhynchosaur cousins, maybe it consumed small tubers and other tough plant parts.

While phytosaurs, metaposaurs and other odd megafauna may dominate our vision of Triassic Connecticut, Colobops and its unique jaw structure remind us that there were just as many unique animals lurking in the undergrowth, though much of their diversity has been hidden from us due to the dearth of good fossils.


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