New information on the early Permian lanthanosuchoid Feeserpeton oklahomensis based on computed tomography

Abstract

The cave deposits of the Lower Permian Richards Spur locality in Oklahoma, USA, have produced an incredible number of terrestrial tetrapod taxa, many of which are currently only known from this locality. One of the many recent taxa to be described from the locality was the small lanthanosuchoid parareptile Feeserpeton oklahomensis. Represented by a well-preserved, near complete skull, F. oklahomensis would have been a small predatory reptile, likely preying upon arthropods, and contributes to the extensive tetrapod fauna that was present at Richards Spur. New computed tomography data of the holotype and only specimen has allowed us to visualize and describe previously obscured and inaccessible anatomy of this taxon. These areas include the mandibular ramus, the palate, the sphenethmoid, the epipterygoids, and the braincase. Furthermore, this new anatomical information allowed formerly unknown character codings to be updated, thus we also performed new phylogenetic analyses that incorporated this new information. The results of these updated phylogenetic analyses are very similar to those of past studies, with F. oklahomensis being found as the sister taxon to all other lanthanosuchoids.

The Making of Calibration Sausage Exemplified by Recalibrating the Transcriptomic Timetree of Jawed Vertebrates

“…First, if Eunotosaurus has moved from the “parareptiles” well outside Diapsida [PN]—or well inside Diapsida, though presumably still in its stem-group ( Ford and Benson, 2019 )—to the turtle stem within the crown group of Diapsida (i.e., Reptilia [PN]), do any other “parareptiles” follow it? The oldest known member of that assemblage, Carbonodraco , comes from the site of Linton in Ohio ( Mann et al, 2019 ), which is about 307–308 Ma old (compare Reisz and Modesto, 1996 ; Carpenter et al, 2015 ), so that should be the minimum age of Archelosauria if all “parareptiles” are archelosaurs; the currently available phylogenetic analyses of “parareptiles” ( Laurin and Piñeiro, 2018 ; MacDougall et al, 2019 ) have not adequately tested this question. While Schoch and Sues (2017) did test the mutual relationships of “parareptiles,” Eunotosaurus , and diapsids and found Eunotosaurus nested in the latter, several nodes away from the former, these nodes were very poorly supported.…”

“…While Schoch and Sues (2017) did test the mutual relationships of “parareptiles,” Eunotosaurus , and diapsids and found Eunotosaurus nested in the latter, several nodes away from the former, these nodes were very poorly supported. The character and taxon samples of all existing matrices for analyses of amniote phylogeny need to be substantially improved ( Ford and Benson, 2018 , 2019 ; Laurin and Piñeiro, 2018 ; MacDougall et al, 2019 ; Mann et al, 2019 ); Ford and Benson (2019) made a large step in that direction, but deliberately excluded Eunotosaurus and the turtles from their analysis so as not to have to deal with all problems at the same time.…”

The making of calibration sausage exemplified by recalibrating the transcriptomic timetree of jawed vertebrates

“…Reptilia [PN]), do any other “parareptiles” follow it? The oldest known member of that assemblage, Carbonodraco , comes from the site of Linton in Ohio (Mann et al, 2019), which is about 307–308 Ma old (compare Reisz and Modesto, 1996, and Carpenter et al, 2015), so that should be the minimum age of Archelosauria if all “parareptiles” are archelosaurs; the currently available phylogenetic analyses of “parareptiles” (Laurin and Piñeiro, 2018; MacDougall et al, 2019) have not adequately tested this question. While Schoch and Sues (2017) did test the mutual relationships of “parareptiles”, Eunotosaurus and diapsids and found Eunotosaurus nested in the latter, several nodes away from the former, these nodes were very poorly supported.…”

“…An Early Triassic or perhaps Late Permian maximum age seems reasonable, but, given the rarity of stem-pan-lepidosaurs and of Permian diapsids in general (Carroll's Gap -Marjanović and Laurin, 2013a), I rather propose to use the ecologically similar small amniotes (e.g. Haridy et al, 2017;MacDougall et al, 2019) Simões et al, 2018Simões et al, , 2020, the pan-squamate record as known today goes completely silent (see below under Node 131 for the one or two supposed exceptions) until the dam suddenly breaks in the Bathonian (Middle Jurassic) and representatives of the stem as well as, by current understanding, several parts of the crown appear in several sites in the northern continents and northernmost Gondwana. Second, these early representatives are all isolated and generally incomplete bones that preserve few diagnostic characters; the oldest complete skeletons come from one Tithonian (latest Jurassic) cluster of sites (Conrad, 2017), followed by a few Early Cretaceous ones as well as the oldest partially articulated material other than Megachirella.…”

“…An Early Triassic or perhaps Late Permian maximum age seems reasonable, but, given the rarity of stem-pan-lepidosaurs and of Permian diapsids in general (Carroll's Gap -Marjanović and Laurin, 2013a), I rather propose to use the ecologically similar small amniotes (e.g. Haridy et al, 2017;MacDougall et al, 2019) of Richards Spur (up to 289.2 ± 0.68 Ma;Woodhead et al, 2010;MacDougall et al, 2017), immediately before Carroll's Gap, to support a soft maximum age of 290 Ma.…”