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~190 Mya Sphenodontian discovered in a drawer.
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erik simpson
Mar 8, 2022, 1:04:08 PM3/8/22
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A remarkably complete fossil unearthed in 1982 has been recently rediscovered in a drawer in Harvard University Museum of Comparative Zoology. From the Kayenta formation (early Jurassic) it is an example of a basal Rhynchocephalian very similar in many ways to the one remaining member of its clade, Tautara. It qualifies as a "living fossil" (very conservative morphlogy).
Abstract:
"Sphenodontian reptiles are an extremely old evolutionary lineage forming the closest relatives to squamates (lizards and snakes) and were globally distributed and more diverse than squamates during the first half of their evolutionary history. However, the majority of their fossils are highly fragmentary, especially within sphenodontines—the group including its single surviving species, Sphenodon punctatus (the tuatara of New Zealand)—thus severely hampering our understanding on the origins of the tuatara. Here, we present a new sphenodontian species from the Early Jurassic of North America (Arizona, USA) represented by a nearly complete articulated skeleton and dozens of upper and lower jaws forming the most complete ontogenetic series in the sphenodontian fossil record. CT-scanning provides plentitude of data that unambiguously place this new taxon as one of the earliest evolving and oldest known sphenodontines. Comparisons with Sphenodon reveal that fundamental patterns of mandibular ontogeny and skeletal architecture in Sphenodon may have originated at least ~190Mya. In combination with recent findings, our results suggest strong morphological stability and an ancient origin of the modern tuatara morphotype."
https://www.nature.com/articles/s42003-022-03144-y
Abstract:
"Sphenodontian reptiles are an extremely old evolutionary lineage forming the closest relatives to squamates (lizards and snakes) and were globally distributed and more diverse than squamates during the first half of their evolutionary history. However, the majority of their fossils are highly fragmentary, especially within sphenodontines—the group including its single surviving species, Sphenodon punctatus (the tuatara of New Zealand)—thus severely hampering our understanding on the origins of the tuatara. Here, we present a new sphenodontian species from the Early Jurassic of North America (Arizona, USA) represented by a nearly complete articulated skeleton and dozens of upper and lower jaws forming the most complete ontogenetic series in the sphenodontian fossil record. CT-scanning provides plentitude of data that unambiguously place this new taxon as one of the earliest evolving and oldest known sphenodontines. Comparisons with Sphenodon reveal that fundamental patterns of mandibular ontogeny and skeletal architecture in Sphenodon may have originated at least ~190Mya. In combination with recent findings, our results suggest strong morphological stability and an ancient origin of the modern tuatara morphotype."
https://www.nature.com/articles/s42003-022-03144-y
Daud Deden
Mar 9, 2022, 7:04:25 AM3/9/22
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erik simpson
Mar 9, 2022, 11:55:51 AM3/9/22
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been thoroughly examined.
Daud Deden
Mar 9, 2022, 7:37:10 PM3/9/22
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