In this paper, we describe two new lizards from the Late Jurassic Morrison Formation. Presenting Eoscincus ornatus, the ornate dawn skink (left), and Microteras borealis (right), the little monster from the north!
These new lizards fill a critical gap in our understanding of squamates when they were just starting to diversify! The Triassic-Jurassic indeed does preserve squamates, but they are usually pretty crushed, which limits their informativeness...
Our lizards show really odd features you would only be able to see with 3D preservation. For example, Eoscincus has giant teeth on the vomers, which forms part of a complete palatal tooth row on the vomer-palatine-pterygoid!
Despite this, both new species are consistently placed at the base of the clade that includes skinks, girdled, and night lizards! Their phylogenetic position indicates early squamate evolution tracks Pangean breakup:
1/13 π¨π¨ I am so excited to present our new paper, six years in the making. Here, we provide the first strong evidence that there is a molecular mechanism behind the origins of living fossil lineages! #biology #science #paleontology academic.oup.com/evolut/advanceβ¦
2/13 Since the early days of modern biology, thinkers like Darwin realized that some living animals and plants seemed to show incredibly low species diversity given their age, as well as few differences from their fossil relatives.
3/13 Yet, there has been no clear evidence for a mechanism behind this pattern, and the term 'living fossil' has fallen out of favor. In 2019, during our first meeting, @TJNear brought up the idea of investigating this pattern using gars, a clade of 7 'living fossil' fishes.