?Pseudocrypturus new species (Eocene Lithornithiformes) + Hapsidopareion (Permian recumbirostran) redescribed + Algorachelus parva (Cretaceous turtle) revised + Megantereon canines

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Some recent non-dino papers:

Free pdf:

?Pseudocrypturus danielsi sp. nov.
?Pseudocrypturus gracilipes sp. nov.

Gerald Mayr & Andrew C. Kitchener (2025)
The Lithornithiformes (Aves) from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK)
Papers in Palaeontology 11(1): e1611
doi: https://doi.org/10.1002/spp2.1611
https://onlinelibrary.wiley.com/doi/10.1002/spp2.1611

 
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.1611


We describe multiple partial skeletons and isolated bones of the palaeognathous Lithornithiformes from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). The well-preserved specimens are assigned to at least four species of the taxa Lithornis and Pseudocrypturus. Two species of Lithornis are identified as L. nasi and L. cf. grandei. The latter species, which was established for fossils from the North American Green River Formation, was initially assigned to the monotypic taxon Calciavis, which is here considered synonymous with Lithornis. Two further new species are tentatively referred to the taxon Pseudocrypturus and are described as ?P. danielsi and ?P. gracilipes. In previous analyses, lithornithiforms most often resulted as the sister taxon of either the Tinamiformes or all crown group Palaeognathae. We detail that current morphological evidence conforms best to a position of these birds outside crown group Palaeognathae and discuss previously unrecognized plesiomorphic features of the foot and pelvis, which support this phylogenetic placement.

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Xavier A. Jenkins, Hans-Dieter Sues, Savannah Webb, Zackary Schepis, Brandon R. Peecook & Arjan Mann (2025)
The recumbirostran Hapsidopareion lepton from the early Permian (Cisuralian: Artinskian) of Oklahoma reassessed using HRμCT, and the placement of Recumbirostra on the amniote stem
Papers in Palaeontology 11(1): e1610
doi: https://doi.org/10.1002/spp2.1610
https://onlinelibrary.wiley.com/doi/10.1002/spp2.1610

Recumbirostra is a clade of heavily modified, superficially lizard-like tetrapods that were originally interpreted as ‘microsaurian lepospondyls’ unrelated to the amniote crown. However, recent work has placed Recumbirostra within Reptilia, based on many similarities between the braincase and postcranium of recumbirostrans with early reptiles. Here, the early Permian hapsidopareiid recumbirostran Hapsidopareion lepton is re-described using high-resolution μCT data of three individuals across distinct ontogenetic stages, including the holotype specimen. These data reveal a suite of similarities with the hapsidopareiid Llistrofus pricei, suggesting that the latter is a subjective junior synonym of Hapsidopareion lepton. Furthermore, we highlight derived features present in Recumbirostra and Amniota that are otherwise absent in early reptiliomorphs, including: a single supraoccipital element that contributes to the endosseous labyrinths, the absence of paired endolymphatic fossae, and the presence of a distinct ampullary fossa between the semicircular canals. We also identify plesiomorphies of the braincase and skull roof of Hapsidopareion that are present in recumbirostrans and early stem-amniotes but lacking in unambiguous crown amniotes. This suggests that features previously uniting recumbirostrans with reptiles are possible symplesiomorphies of Amniota, and a new phylogenetic analysis places Recumbirostra as a crownward group along the amniote stem, more derived than traditionally recognized reptiliomorphs such as Seymouria. Our findings highlight the need for further anatomical and descriptive studies of both stem- and crown-group amniotes, and specifically the need for further revisions to those taxa originally regarded as ‘microsaurs’.

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Free pdf:

Adán Pérez-García (2025)
A taxonomic revision of the Cenomanian bothremydid turtle Algorachelus parva from Israel and morphological variation within its genus.
Palaeontologia Electronica, 28(1):a2.
https://doi.org/10.26879/1398
https://palaeo-electronica.org/content/?view=article&id=5424:a-bothremydid-turtle-in-israel&catid=707


The bothremydid turtle Algorachelus is identified as the oldest lineage of pelomedusoid turtles (Pleurodira) that dispersed from Gondwanan to Laurasian regions. It is recognized in the Cenomanian (early Late Cretaceous) of the Middle East (in Israel), Europe (in the Iberian Peninsula), and North America (in Utah). The European and North American species were identified and defined less than 10 years ago. However, two putative different species, originally attributable to the genus Podocnemis (i.e., a member of Podocnemididae now identified as exclusive to South America), were defined in the lower or middle Cenomanian levels of the ‘Ein Yabrud limestone quarry (Binyamin Region, West Bank, Israel). Over almost 50 years, no new data on the Cenomanian taxon or taxa of Bothremydidae from Israel have been published. A detailed first-hand review of the previously documented material is presented here. Several errors in the anatomical interpretation of these specimens are corrected. Unpublished articulated and well-preserved specimens from the type locality are analyzed. Characters not yet defined for the bothremydid or bothremydids from Israel, but essential for the comparison with those of Europe and North America, are studied. In addition, several anatomical regions hitherto not analyzed for the Israeli material, some of them being poorly known for Algorachelus (such as the skull) or never documented for this genus (such as the lower jaw), are analyzed. The presence of a single species in Israel is justified, being recognized as Algorachelus parva. Intraspecific variability is recognized. An emended diagnosis is proposed for this species, which belongs to a remarkably successful lineage of pleurodires that is characterized by its long persistence and multicontinental geographic range.

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Free pdf:

Mauricio Antón, Gema Siliceo, Juan Francisco Pastor, Qigao Jiangzuo & Manuel J. Salesa (2024)
Exposed weapons: A revised reconstruction of the facial anatomy and life appearance of the saber-toothed cat Megantereon (Felidae, Machairodontinae)
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.25622
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25622

Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25622


Megantereon was a widespread saber-toothed felid from the Pliocene and Pleistocene of the Old World and North America, but its rarity in the fossil record makes it complicated to restore its life appearance. Lack of complete specimens makes it necessary to combine information from fossils of different individuals to reconstruct their facial anatomy. In this work, we combine the analysis of skulls and mandibles of Megantereon from various fossil sites with the study of extant carnivorans through dissection, 3D scans, and the observation of live individuals. Megantereon combined very elongated upper canines with mandibular flanges that were not deep enough to match the length of the sabers, as well as a wide maxilla combined with narrow incisor rows and mandibular symphysis. Such features are compatible with the presence of exposed canines in life, because the narrow symphysis allows room to accommodate lips and other soft tissues medial to the sabers, while the protrusion of the tips of the upper canines beyond the mental flanges makes it unlikely that they would be enveloped in soft tissue sheaths, which would dangle with the inherent risk of puncture. Megantereon was transitional between saber-toothed felids with covered upper canines, where saber length fits with mental flange depth, and the derived Smilodon where the upper canines are much longer than the flanges and the lips fit between upper canines and mandible, leaving the upper canine crowns largely exposed in life.

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