Carnotaurus joins the LRT

Everyone knows Carnotaurus
(Fig. 1; Bonaparte 1985, Bonaparte, Novas and Coria 1990), the slender theropod with skull horns. In the large reptile tree (LRT, 1391 taxa) Carnotaurus nests with Majungasaurus, members of the first clade of giant theropods, the one that includes Spinosaurus, Allosaurus, Ceratosaurus and many others.

That comes as no surprise.
The only contribution I can make to this popular dinosaur is to note the horns arise from laterally extended lacrimals and prefrontals, not laterally extended frontals, as originally proposed (Fig. 1). In stating this, I may be late to the party. If others have already published on this bit of trivia, I am not aware of it. If so, let me know.

Figure 1. Carnotaurus skull from Bonaparte, Novas and Coria 1990 with colors added. Note the traditional frontals are much reduced here. Here the horns are comprised of the lacrimals + prefrontals in patterns typical of basal theropods.

Carnotaurus sastrei (Bonaparte 1985; Bonaparte, Novas and Coria 1990; Late Cretaceous, 70 mya; 7.5m in length) is an abelisaurid theropod dinosaur related to Majungasaurus. Carnotaurus had a shorter, upturned snout, a shorter mandible, frontal horns, a deeper jugal, a narrower skull (below the horns) and a down-turned naris.

References
Bonaparte JF 1985. A horned Cretaceous carnosaur from Patagonia. National Geographic Research. 1 (1): 149–151.
Bonaparte JF, Novas FE and Coria RA 1990. Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia. Contributions in Science. 416: 1–41. PDF

Pholidocercus: a long tailed armadillo-mimic hedgehog

Updated July 25, 2022
with a new nesting for Pholidocercus close to Leptictis.

According to Wikipedia,
“Pholidocercus is an extinct monotypic genus of mammal from the Messel pit related to and resembling the modern-day hedgehog with a single species, Pholidocercus hassiacus. Like the hedgehog, it was covered in thin spines. Unlike hedgehogs, it had scales on its head in a helmet-like formation, and had a long, thick, scaled tail.”

Here
in the large reptile tree (LRT, 2122 taxa) Pholidocercus (von Koenigswald & Storch 1983, Figs 1, 2) nests with Leptictis (Figs 3, 4), a basal Oligocene placental in the lineage of (some) elephant shrews (=sengis), tenrecs and odontocetes.

Figure 1. Only one of the several Messel Pit Pholidocercus specimens. This one has a truncated tail and a halo of soft tissue (pre-spines).

Pholidocercus hassiacus 
(von Koenigswald & Storch 1983; HLMD Me 7577; Middle Eocene) is an extinct sister to Leptictis. Known from several fossils, Pholidocercus has a long thick tail provided with tall neural spines and deep chevrons. The rostrum is short. Soft tissue is preserved as scales on the head in a helmet-like formation and scales on the tail, a pattern convergent with armadillos.

Figure 3. Leptictis skull. Note the change in premolar identity.

Leptictis acutidens
(Leidy 1868, Rose 2006, early Oligocene) is an extinct elephant shrew nesting between the coatimundi, Nasua, and Rhynchocyon. Anagale is a close relative. All are basal placentals with four molars and three premolars. The tail was probably longer than preserved. The tiny manus appears to have only three digits. Note the large calcaneal heel, a trait usually found in digitigrade running mammals, like Rhynchocyon. This clade is basal to odontocete whales like Orcinus.

Figure 4. Extant Nasua, the extant coatimundi, is basal to Pholidocercus, Leptictis and extant Rhynchocyon, the elephant shrew.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here… and the ‘housekeeping‘ of placentals continues.

References
von Koenigswald W and Storch Gh 1983. Pholidocercus hassiacus, ein Amphilermuride aus dem Eozan der “Grube Messel” bei Darmstadt (Mammalia: Lipotyphla). Senchenberg Lethaia 64:447–459.

wiki/Hedgehogs
wiki/Erinaceus
wiki/Echinops
wiki/Pholidocercus

Mongoose trifles

Herpestes, the Egyptian mongoose, 
 (Linneaus 1758; extant; 48-60cm in length) has large carnassials. Herpestes is a lower, shorter-legged ancestor to the raccoon, Procyon, with a relatively shorter rostrum and longer, lower body. Surprisingly, the postfrontal and postorbital are elongated here.

Figure 1. The Egyptian mongoose, Herpestes, develops a postorbital bar arising from the layered postfrontal and postorbital reappearing in this clade. The lacrimal and prefrontal are separated here.

Eupleres from Madagascar 
(Doyère 1835) is the extant Western falnouc, a cat-like mongoose from Madagascar. Note the elongate premaxilla, the gracile mandible, the reduced canine and other rodent-like traits. No postfrontal or postorbital appears here.

Figure 2. Eupleres is a Madagascar mongoose with a long, tree-shrew-like skull with a longer premaxilla and smaller, more widely-space, primitive teeth. No postfrontal or postorbital appears here.

Despite the differences in these two taxa,
the large reptile tree nests them in the same clade along with Prohesperocyon, the Late Eocene pre-mole, and Talpa the living mole (a member of Carnivora, not Insectivora).

References
Doyére LMF 1835. Notice sur un mammifére de Madagascar, formant le type d’un nouveau genre de la famille des Carnassiers insectivores de M. Cuvier. Ann. Sci. Nat. Zool. 4: 270–283.
Linnaeus C von 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

Vestigial fingers on the UNSM 93000 Nyctosaurus

The UNSM 93000 specimen attributed to Nyctosaurus
has only three wing phalanges and the tiny vestigial free fingers have never been looked at using DGS methods before. Well, here they are (Fig. 1).

Figure 1. Closeup of the UNSM 93000 specimen of Nyctosaurus focusing on three vestige free fingers. This is what happens when you no longer need these fingers. You can tell Nyctosaurus from Pteranodon in that the former never fuses the sesamoid (extensor tendon process) to phalanx 4.1. Other wrongly consider this a trait of immaturity.

Nyctosaurus sp. UNSM 93000 (Brown 1978, 1986) was derived from a sister to Nyctosaurus gracilis and phylogenetically preceded the crested Nyctosaurus specimens. Except for the rostral tip, the skull and cervicals are missing. Distinct from Nyctosaurus gracilis, the dorsals of the Nebraska specimen relatively shorter. The scapula and coracoid were more robust. The deltopectoral crest of the humerus most closely resembled that of Muzquizopteryx. Fingers I-III were tiny vestiges. Manual 4.1 extended to mid ulna when folded. Manual 4.4 was probably fused to m4.3 or it was missing and m4.3 became curved.

Figure 2. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

The pubis and ischium did not touch, as in more primitive nyctosaurs. It would have been impossible for the forelimb to develop thrust during terrestrial locomotion. It was likely elevated or used like a ski-pole.

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The family tree of the Ornithocephalia and Germanodactylia is here. The expanded family tree of the Pterosauria is here.

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References
Brown GW 1978. Preliminary report on an articulated specimen of Pteranodon Nyctosaurus) gracilis. Proceedings of the Nebraska Academy of Science 88: 39.
Brown GW 1986. Reassessment of Nyctosaurus: new wings for an old pterosaur. Proceedings of the Nebraska Academy of Science 96: 47.

 

Roundtable discussion on YouTube: How to be a scientist

I quote-mined the round table video conversation below.

1. Host Carl Zimmer, author
2. Panelist Mariette DiChristina, editor-in-chief, Scientific American
3. Panelist Dany Spencer Adams, developmental biologist
4. Panelist Ivan Oransky, journalist
5. Panellist Massimo Pigliucci, biologist, philosopher

Video caption:
“As a discipline, science aspires to be an evidence-based, non-partisan tool for revealing truth. But science is carried out by scientists, human beings like the rest of us, subject to pressures, preconceptions, and biases. What are the external, non-scientific forces that impact scientific research? Does the current research structure drive focus away from unbiased exploration? What lessons can we draw from the recent crisis of reproducibility afflicting some research areas? In this program, experts discuss the myriad factors scientists face in a highly competitive environment as they seek to uphold and advance the ideals of scientific exploration.”

According to Massimo Pigliucci:

1. “Write your materials and methods first, then your results, then your introduction last.”
2. “Overcome confirmation bias. What if your result is something that is not predicted?”
3. “There’s no incentive to replicate someone else’s results. You want to be the first one to get there. Not the second one. Most journals, especially the high-impact journals want the novel stuff, the sexy stuff, the stuff that nobody’s done before. [Even so…] Two-thirds of papers in top journals never get cited within five years. 
4. “There are 150 applicants for every paid position.” 
5. Some scientists want to see and approve pre-published stories, to check their quotes. 
6. Blogposts represent the direct voice of the scientist. Historically this has been a problem because you’re wasting your time, andyou’re not including other scientists. 

According to Dany Spencer Adams:

1. “Science is one way of learning things.”
2. “If you’re not failing most of the time, you’re not working hard enough.”
3. “Don’t send anything from a Mac to a PC. Don’t update your software within a week of your deadline. Formatting to a journal’s style takes time. Reformatting from one journal to another (after the first rejection) takes more time.”
4. “Only the top 4 percent of applications receive funding from the NSF.” 

According to Ivan Oransky:

1. “Ask yourself, How can I prove myself wrong?”
2. “If a paper is published and no one cites it, does it really matter? So getting published in high-impact journals is important in Academia.”
3. The number of retractions (from fraudulent data collection or misconduct) has dramatically increased, but remains relatively rare. Current record holder: 183 retractions from a single individual. Falsification, Fabrication and Plagiarism: the Triad. Some authors were caught doing there own peer-review, or each others’ peer-reviews in cooperation. His ‘Doing the Right Thing Award’ is given to those who make corrections at some cost to themselves.”

According to Carl Zimmer:

1. “Much time is spent filling out paperwork to get grants.”
2. “Are journalists part of the problem?” 

According to Mariette DiChristina:

1. “Science tries to embrace corrections.
2. “Materials and methods should produce replicable results.
3. “Many of us are click-bait chasers. Invite the researcher to tell the story of how the results came to be, describe the human endeavor. Provide the context.”

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In the old days:
scientists simply wrote their papers without grants, without referees, without competing for journal pages, without waiting for months or years for all this to take place. There were far fewer scientists working back then, and there was more ‘low-hanging fruit’ waiting to be plucked (= discovered). Then again, new ideas were still ridiculed until confirmed.

Today:
scientists produce blogposts, send unpublished, unrefereeed PDFs to ResearchGate.org and write books. Others publish without referees, competing for grants, dealing with students, dealing with administrators, principal investigators or all of the above. Some scientists making contributions are not PhDs.

Readers should gather by now
that sometimes scientists make mistakes, often by the sin of omission (= taxon exclusion) and due to that, they sometimes come to improper conclusions. This happened in the past and it continues to happen in the present. When I make mistakes I correct them. It’s part of the learning process. If nothing else, I hope that readers will take from this blog the idea that all hypotheses should be questioned and all conclusions should be tested. It’s okay to do this, no matter how many PhDs are listed as co-authors. Tradition can be wrong. Sometimes people will despise you for upsetting favorite traditions. A long list of well-known scientists have been despised for their views, hypotheses and theories.

Don’t wait.
The ‘low-hanging fruit’ is quickly disappearing with every new discovery. This is a golden era in paleontology that will someday dry up as questions are answered and topologies are cemented.

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Side note:
Panelist Mariette DiChristina was the online editor-in-chief at Scientific American where Dr. Darren Naish published his Tetrapod Zoology blogpost for several years. Recently they parted ways and Dr. Naish has reported a new interest in non-tetrapod vertebrates (= fish).

I’d like to see Dr. Naish continue his interest in tetrapods, perhaps to ultimately create a wide gamut cladogram of tetrapods and compare it to the results recovered by the large reptile tree at ReptileEvolution.com, which he continues to disparage. Let’s all hope Dr. Naish is not a subscriber to Massimo Pigliucci’s statement #3 (above). To that point, as everyone knows, in EVERY CASE I am ‘the second one’ to describe a taxon. Even so, and as proven here, there are still a good number of discoveries to be made out there.

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Last minute addition:
Dr. Steve Brusatte how new discoveries are presented in the press.

A basal hupehsuchid with a duckbill: YAGM V 1401

Updated September 30, 2021
with new tracings and nesting the YAGM specimen between Wumengosaurus and the rest of the Ichthyopterygia, basal to hupehsuchids.

Cheng et al. 2019
bring us news of a new armored Early Triassic (250 mya) specimen (YAGM V 1401; Figs. 1,2) they attribute to the armored Early Triassic hupehsuchid, Eretmorhipis carrolldongi (Fig. 5; holotype WGSC V26020; Chen et al. 2015). The holotype specimen lacks a skull. The authors considered the new YAGM specimen, complete with skull, conspecific with the WGSC holotype of Eretmorhipis, noting it had small eyes relative to the body and a duckbill-like rostrum.

Instead
the large reptile tree (LRT, 1389 taxa then 1944 taxa now; Fig. 3) nests the YAGM specimen basal to the clade of hupehsuchids, close to Wumengosaurus.

The eyes are actually large relative to the skull,
in the new YAGM specimen (Fig. 2), but the skull is tiny relative to the body. The rostrum is narrow relative to the cranium. Typically that enables binocular vision. The authors did not provide a reconstruction of the skull.

The wide, flat rostrum of the YAGM specimen has an open central area,
like Ornithorhynchus the duckbill platypus (Fig. 4) by convergence. Given that bit of morphology the authors sought to extend the duckbill analog by reporting small eyes relative to the body in the YAGM specimen. That gives them an irrefutable headline, but a little mis-leading given the reconstruction (Fig. 2). The authors suggest Eretmorhipis used mechanoreceptors in the rostrum instead of eyesight. They report, “Apparent similarities include exceptionally small eyes relative to the body, snout ending with crura with a large internasal space, housing a bone reminiscent of os paradoxum, a mysterious bone of platypus, and external grooves along the crura.” That’s pretty awesome! Larry Martin would have enjoyed this list of convergent traits. I have no idea how the ox paradoxum bone fit in the YAGM specimen skull. So it remains a paradox.

Figure 1. Eretmorhipis in situ and line drawing from Cheng et al. 2019. Colored here using DGS methods. Some bones are reidentified here. See figure 2 for matching colors.

The authors created a chimaera
when they added the hands and feet of the holotype WGSC specimen to the new YAGM specimen in their Nature paper. Since the two specimens are not related, that is going to cause confusion. No matter how sure they were, the authors needed a valid phylogenetic analysis to nest their new specimen, now requiring a new generic and specific name.

Figure 2. Reconstruction of Eretmorhipis skull from figure 1, along with in situ specimen and reconstruction from Cheng et al. 2019. Pectoral and pelvic girdles magnified and colored using DGS methods. The skull appears to provide binocular vision due to the narrow rostrum and wide cranium.

Traditional paleontologists need to catch up to the LRT
and start including thalattosauriforms and mesosaurs whenever they study basal ichthyopterygians, like hupehsuchids. Basal taxa are all closely related and all three taxa include a wide variety of morphotypes, including some that converge.

Figure 4. Ornithorhynchus skull with colors added using DGS methods. Note the large opening in the dorsal view of the rostrum, as in Eretmorhipis, by convergence.

It’s also worth noting
that the YAGM specimen has a cleithrum and a ventrally broad clavicle along with an interclavicle and other traits lacking in hupehsuchids.

Figure 5. The holotype specimen of Eretmorhipis carrolldongi WGSC V26020 compared to scale to the figure drawn form Cheng et al. 2019 for specimen YAGM V 1401. Cheng et al. created a chimaera when they added the WGSC specimen hands and feet to the new YAGM specimen without first nesting them together in a cladogram. These two specimens do not nest together in the LRT despite the massive convergence. Don’t try to eyeball taxa. Let the software take the bias out of it.

A word to workers: Don’t try to ‘eyeball’ taxa.
Let the phylogenetic software take the bias out of making a taxonomic determination. We’ve seen professional workers make this mistake before by combining diphyletic turtles, whales, seals, and by miss-nesting Vancleavea, Lagerpeton, Chilesaurus, Daemonosaurus by taxon exclusion. Let’s not forget those who keep insisting that pterosaurs are archosaurs (virtually all traditional workers), again by omitting pertinent taxa.

Figure 6. Mesosaurus origins recovered by the LRT. The fossil record appears to be topsy turvy here with the basal taxa appearing 30 million years later. Fossils are rare and discovery is rarer. Things like this sometimes happen. The YAGM specimen is large, like Mesosaurus, but later (at 250 mya) than Thadeosaurus.

References
Chen X-H, Motani R, Cheng L, Jiang D-Y and Rieppel O 2015. A new specimen of Carroll’s mystery hupehsuchian from the Lower Triassic of China. PLoS One 10, e0126024, https://doi.org/10.1371/journal.pone.0126024 (2015).
Cheng L, Motani R, Jiang D-Y, Yan C-B, Tintori A and Rieppel O 2019. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Nature Scientific Reports Published online January 24, 2019.

Crocodylomorph study omits a long list of basal taxa

Wilberg, Turner and Brochu 2019
bring us the “evolutionary structure and timing of major habitat shifts in Crocodylomorpha.” 

Unfortunately
Wilberg, Turner and Brochu 2019 omitted a long list of basal bipedal crocodylomorpha (Figs. 1, 2), and considered an ingroup, Gracilisuchus, an outgroup. They also considered the unrelated giant rauisuchid, Postosuchus, an outgroup taxon.

Missing from the Wilberg, Turner and Brochu study
are a number of basal Crocodylomorph taxa and their outgroups, as determined by a wide gamut analysis of reptiles (= the large reptile tree = LRT; subset Fig. 1).

Ingroup Crocodylomorpha in the LRT
omitted by Wilberg, Turner and Brochu include: YPM VP 057 103, Pseudhesperosuchus, Carnufex, Trialestes, Lewisuchus, MCZ 4116, Saltopus, Scleromochlus, SMNS 12591, Terrestrisuchus, Tarjadia, Parringtonia, Litargosuchus, Erpetosuchus, SMNS 12352, Pedeticosaurus, Yonghesuchus, Dromicosuchus, Saltoposuchus and Dyoplax.

Outgroups to the clade Crocodylomorpha in the LRT omitted by Wilberg, Turner and Brochu include: Herrerasaurus + Staurikosaurus (at the base of the Dinosauria), PVL 4597 (at the base of the Archosauria = Crocodylomorpha + Dinosauria), Turfanosuchus (proximal outgroup to Archosauria), Decuriasuchus + Pagosvenator (second proximal outgroup to Archosauria).

Figure 2. Subset of the LRT focusing on Crocodylomorpha.

Figure 1. Subset of the LRT focusing on the Crocodylomorpha, dorsal scutes, elongate proximal carpals, bipedality and clades.

Simply adding taxa
solves all these problems and documents a more gradual accumulation of derived traits and major habitat shifts.

Figure 2. Ten basal bipedal crocodylomorphs descending from a sister to Decuriasuchus.

References
Wilberg EW, Turner AH and Brochu CA 2019. Evolutionary structure and timing of major habitat shifts in Crocodylomorpha. Nature.com/scientificreports DOI:10.1038/s41598-018-36795-1

wiki/Crocodylomorpha

Early Permian Cabarzia enters the LRT on two legs

Spindler, Werneberg and Schneider 2019
bring us news of a new headless, but otherwise complete skeleton from the Early Permian of Germany. The authors considered Cabarzia trostheidei (Figs. 1, 2, 5; NML-G2017/001) a close match to the Middle Permian protodiapsid Mesenosaurus (Fig. 2) from the Middle Permian of Russia and the oldest evidence for bipedal locomotion, 15 million years earlier than Eudibamus.

Figure 1. Cabarzia in situ and tracing distorted to match the photo from Spindler, et al. 2019. Inserts show manus and pes with DGS colors and reconstructions. Scale bar = 5 cm. Pelvis enlarged in figure 4.

In slight contrast
the large reptile tree (LRT, 1385 taxa; subset Fig. 4) nests Cabarzia on the synapsid side of the Synapsida-Protodiapsida split within the new Archosauromorpha. Skull-less Cabarzia nests with the synapsids, Apsisaurus and Aerosaurus, also from the Early Permian. This is only a node or two away from Mesenosaurus.

In an earlier Spindler et al. 2016 phylogenetic analysis,
the last outgroup to the Synapsida-Protodiapsida split, Vaughnictis nested with the new Lepidosauromorpha caseid, Oedaleops (Fig. 3) far from the synapsids, but close to Feeserpeton and other taxa with a lateral temporal opening not related to synapsids. That error and the mistaken monophyly of the clade Varanopidae, are common to in all current paleontological books. Both are due to taxon exclusion at the base of the Reptilia (see below) and the lack of diapsid taxa in synapsid studies and vice versa.

Figure 2. Two specimens attributed to Mesenosaurus compared to scale with Cabarzia. Scale bar = 5cm.

Spindler et al. 2016 (the Ascendonanus paper)
presented a phylogenetic analysis that included Vaughnictis, which nested with the Lepidosauromorph caseid, Oedaleops, (Fig. 3) without providing enough taxa to recover a basal Lepidosauromorpha-Archosauromorpha split recovered by the LRT that separates caseids from synapsids and nests them with other bulky herbivores with a lateral temporal fenestra, like Eunotosaurus. Cabarzia was then known as the Cabarz specimen, then considered a member of the Varanopidae (Fg. 3).

FIgure 3. Spindler et al. 2016 cladogram suffering from massive taxon exclusion. The red panel highlights taxa that nest within the new Lepidosauromorpha in the LRT. The dark gray panel highlands various actual and putative varanopids nesting paraphyletically. In the LRT they nest together. Note the proximity of the Cabarz specimen (Cabarzia) to Elliotsmithia, but some distance from Apsisaurus, Aerosaurus, Varanops and and Varanodon.

The LRT
(subset Fig. 4) does not suffer from taxon exclusion. At least, so far… Rather this wide gamut study illuminates previously unrecognized splits, like those within the traditional Varanopidae that produced the Protodiapsida.

Figure 4. Subset of the LRT focusing on basal Archosauromorpha including Cabarzia nesting at the base of the -Synapsida. Note all the large varanopids nest together here in the Synapsida, separate from small varanopids in the Protodiapsida.

Bipedal locomotion
Spindler et al. report, “Although the proportions of the entire postcranium of Cabarzia roughly resemble those of Eudibamus, these genera can easily be distinguished based on their vertebrae.” 

Citing Berman et al. 2000b and Sumida et al. 2013,
Spindler et al. list the adaptations of functional bipedalism. (my notes added)

1. short neck (but Chlamydosaurus has a long neck)
2. long hindlimbs
3. short forelimbs
4. short and slender trunk
5. and a long robust tail (but Chlamydosaurus has a long attenuated tai)
6. a rearward shift of the center of body mass

Spindler et al. 2018 note: “Decreased asymmetry of the hindlimb is seen in basal varanopids and mesenosaurines. Eudibamus has remarkably narrow caudal vertebrae; this may indicate that it evolved active bipedalism, facilitating slow bipedal locomotion.” We talked earlier here about the basal diapsid with a long neck and super slender tail, Eudibamus and its putative bipedal abilities. Spindler et al. do not cite the most active scientist currently working with bipedal lizards, Bruce Jayne and his video of lizards on treadmills.

FIgure 4. Pelvis of Cabarzia colored with DGS. Note the offset right femoral head perforating the pelvis, the anterior processes of the illi a and the four sacral vertebrae, all pointing to bipedal locomotion. Some of this was overlooked by Spindler et al. The left femur is too long due to the split. The pink linear bones are probably displaced gastralia.

The traditional touchstones of bipedal locomotion in lizards
(e.g. Chlamydosaurus kingii) are also present in Cabarzia. These include (according to Shine and Lambeck 1978, Snyder 1954; my notes added in bold):

1. Bipedal reptiles are generally small, having experienced phylogenetic miniaturization –  outgroup taxa, Protorothyris and Vaughnictis, are not larger than Cabarzia.
2. Bipeds are terrestrial and/or arboreal – present in most tetrapods
3. Longer hind limbs than forelimbs – present in many tetrapods
4. Anterior process of the illiim, no matter how small – present in Cabarzia 
5. Typically stronger or more sacral connections to the ilium – present in Cabarzia 
6. Typically a long neck and short torso – unknown in Cabarzia 

In Cabarzia we also find

1. perforated acetabulum
2. elongate and offset cylindrical femoral head

Overlooked by Spindler et al.:
Cabarzia provides a more complete look at the post-crania of basalmost synapsids, which include humans. No one has ever considered the possibility that bipedal locomotion in the Early Permian was part of that story. It is also common knowledge that more derived taxa in the lineage of synapsids, therapsids and mammals retained  quadrupedal locomotion, an imperforated acetabulum and only two sacrals. So bipedalism was a dead-end for Cabarzia, producing no known ancestors.

Figure 5. Cabarzia compared to Vaughnictis and Apsisaurus to scale. Finger 1 and other phalanges were identified in published photos of this specimen (Fig. 1) using DGS tracing and reconstruction methods.

Despite the similar and coeval red bed matrices
of Aerosaurus, Apsisaurus, Vaughnictis and Cabarzia, the former three come from the western USA (Colorado) while Cabarzia comes from central Germany. Back then they were closer to one another, not separated by an Atlantic Ocean (Fig. 6).

Figure 6. Early Permian Earth, prior to the separation of Europe from North America.

References
Shine R and Lambeck R 1989.Ecology of Frillneck Lizards, Chlamydosaurus kingii (Agamidae), in Tropical Australia. Aust. Wildl. res. Vol. 16: 491-500.
Snyder RC 1954. The anatomy and function of the pelvic girdle and hind limb in lizard locomotion. American Journal of Anatomy 95:1-46.
Spindler F, Werneberg R and Schneider JW 2019. A new mesenosaurine from the lower Permian of Germany and the postcrania of Mesenosaurus: implications for early amniote comparative osteology. PalZ Paläontologische Gesellschaft

 

Big, bad Dinohyus (= Daedon) enters the LRT

No surprises here.
Daeodon shoshonensis (Cope 1878), the last and largest of the entelodonts, nests with Archaeotherium in the large reptile tree (LRT, 1383 taxa). A huge skull and slender limbs tipped by two fingers and two twos characterize this genus. A bison-like hump of dorsal spines helped support the mighty skull.

Figure 1. Skull of Dinohyus + Daedon with bones colored using DGS. Note the reappearance of the postorbital ring composed of postfrontal and postorbital. The jugal extends to the jaw joint, something that usually only happens in marsupials. The jaw joint is at the back of the skull, convergent with some multituberculates, crowding out the ear bones. Not much of ascent on that coronoid process of the dentary. And is that a splenial poking out as a mandible horn?

Repeating the caption here:
Note the reappearance of the postorbital ring composed of postfrontal and postorbital. The jugal extends to the jaw joint, something that usually only happens in marsupials. The jaw joint is at the back of the skull, convergent with some multituberculates, crowding out the ear bones. Not much of ascent on that coronoid process of the dentary. And is that a splenial poking out as a mandible horn?

Entelodonts arise from
a sister to Ancodus in the LRT. And this clade is a sister to the camel + deer + giraffe clade. All arise from sisters to Danjiangia and Lambdotherium in the LRT. And all these are sisters to Sus, the pig, a basal artiodactyl.

References
Cope ED 1878. On some characters of the Miocene fauna of Oregon. Paleontological Bulletin. 30: 1–16.
Peterson O A 1905b. A correction of the generic name (Dinochoerus) given to certain fossil remains from the Loup Fork Miocene of Nebraska. Science. 22: 719.
Peterson OA 1909. A revision of the Entelodontida”. Memoirs of the Carnegie Museum. 4 (3): 41–158.

wiki/Anthracotherium
wiki/Archaeotherium
wiki/Daeodon

 

The most basal lepidosauriforms and lepidosaurs to scale

Lepidosauriform fossils are extremely rare in the Mesozoic and Paleozoic.
In the Earliest Permian we find Tridentinosaurus (Fig. 1; Dal Piaz 1931,1932; Leonardi 1959), a taxon ancestral to the pseudo-rib-gliders of the Late Permian (Coelurosauravus) through the Early Cretaceous (Xianlong) and close to the origin of all other lepidosauriforms, including living snakes, lizards and the tuatara (genus: Sphenodon).

Figure 1. Basal lepidosauriformes to scale from Tridentinosaurus (Earliest Permian) to Huehuecuetzpalli (Early Cretaceous). Subtle differences lump and split these taxa into their various clades.

 

Sometime during the Early Permian
the Lepidosauria split between the Sphenodontia + Drepanosauria and the Tritosauria + Protosquamata in the large reptile tree (LRT, 1381 taxa).

Short-legged
Jesairosaurus, in the Early Triassic, nests basal to the clade of slow-moving, arboreal drepanosaurs. On another branch, Megachirella (Middle Triassic) and Gephyrosaurus (Early Jurassic) are basal members of the Sphenodontia.

Long-legged
and probably arboreal Saurosternon and Palaegama, (both Late Permian) are the earliest known Lepidosauria, but they are basal to the Tritosauria + Protosquamata clades.

Figure 5. Subset of the LRT focusing on the Tritosauria. Note the separation of one specimen attributed to Macrocnemus.

Late-surviving, long-legged basal Tritosauria
include tiny Tijubina and Huehuecuetzpalli (both Early Cretaceous). This clade gave rise to giant Tanystropheus, exotic Longisquama and volant Pteranodon.

Tiny and long-legged Late Permian
Lacertulus is the basal taxon in the previously unrecognized clade Protosquamata, the parent clade to the extant Squamata. This taxon documents the antiquity of this clade.

Going back to the Early Permian
we have a long-torso, short-legged specimen, MNC TA-1045, that nests in the LRT just outside the extant Squamata (Iguana). MNC TA-1045 was found alongside the genus Ascendonanus (MNC-TA0924), a basal archosauromorph diapsid with a shorter torso you can see here. The MNC TA-1045 specimen pushes the genesis of the lepidosaurs back to the Early Permian, nearly coeval with the basalmost lepidosauriform shown in figure 1, Tridentinosaurus.

The Lepidosauromorph-Archosauromorph dichotomy
was already present in the Viséan (Early Carboniferous, 330 mya), so the new Lepidosauromorpha had 30 million years to diverge into captorhinomorphs, diadectomorphs, millerettids and lepidosauriforms by the time Tridentinosaurus first appears in the Earliest Permian (300 mya).

Late surviving,
but basalmost lepidosauromorphs include Sophineta , Paliguana and Coletta (all Early Triassic). These taxa have an upper temporal fenestra not seen in outgroup taxa.

Proximal outgroups for the Lepidosauriforms
include the late-surviving owenettids: Barasaurus (Late Permian) and kin, Owenetta (Late Permian) and kin, and the late-surviving macroleterids (Middle Permian) and nycteroleterids (Middle Permian) before them.

At least that’s what the data says so far.
With every new taxon the tree grows stronger and more precise, so the odds of changing the tree topology with additional taxa continue to drop. Looking forward to seeing more Paleozoic arboreal lepidosauromorph discoveries as they arrive.

References
Dal Piaz Gb. 1932 (1931). Scoperta degli avanzi di un rettile (lacertide) nei tufi compresi entro i porfidi quarziferi permiani del Trentino. Atti Soc. Ital. Progr. Scienze, XX Riunione, v. 2, pp. 280-281. [The discovery of the remains of a reptile (lacertide) in tuffs including within the Permian quartz porphyry of Trentino.]
Leonardi P 1959. Tridentinosaurus antiquus Gb. Dal Piaz, rettile protorosauro permiano del Trentino orientale. Memorie di Scienze Geologiche 21: 3–15.

www.reptileevolution.com/reptile-tree.htm