Whale-Lizards of the Triassic III: Revenge of Eretmorhipis

You might fondly remember the two previous posts in this series: Part I and Part II which describe a particularly bizarre group of basal ichthyosauromorphs called hupehsuchians. Known for their "bony body tubes" and wide, toothless mouths, hupehsuchians are a surprisingly diverse group that includes five monospecific genera: Nanchangosaurus, Hupehsuchus, Eohupehsuchus, Parahupehsuchus, and Eretmorhipis. Eretmorhipis is the most recently-described hupehsuchian (Chen et al. 2015) but also one of the more mysterious, as the holotype does not include a skull or even cervicals. I should mention this is also the case with Parahupehsuchus although it's missing most of the tail, too.

Whale Lizards of the Triassic: Part II

A gorgeous new specimen of Hupehsuchus (ZMNH M8127).

When last we discussed Hupehsuchians, I ran down the known genera and went a bit into their lifestyle and phylogenetic relationships. The short version: these are small marine reptiles that are allied with ichthyosaurs in a monophyletic Ichthyosauriforms. They are long-snounted, toothless, filter-feeding creatures with closely-knit ribs and gastralia that form various degrees of “bony body tubes” across genera. They all lived around the same time, in the same place. Although they are taxonomically diverse, they are morphologically conservative.

Whale Lizards of the Triassic, Part I

How many modern marine reptiles can you name? I count two, broadly speaking: sea turtles and marine iguanas. Back in the Cretaceous, there were a few others. Many of the world’s oceans hosted the deadly mosasaurs, which were essentially marine-adapted monitor lizards. You also had the familiar but puzzling plesiosaurs; with their long necks, tiny heads, and wide rounded bodies, it’s still difficult to determine exactly how they made their living. Also still going strong were the ichthyosaurs—dolphin-shaped marine lizards with huge eyes and a taste for cephalopods. Marine iguanas weren’t a thing yet, but sea turtles were actually more diverse (and bigger) than they are today.