Besanosaurus (Middle Triassic ichthyosaur) fetus fossil + Aelurognathus (Permian gorgonopsian) new skeleton (free pdfs)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Recent papers not yet mentioned:

Free pdf:

Feiko Miedema, Gabriele Bindellini, Andrzej S. Wolniewicz, Erin E. Maxwell & Cristiano Dal Sasso (2026)
An in utero foetus of the Middle Triassic ichthyosaur Besanosaurus leptorhynchus from Monte San Giorgio, Italy.
Fossil Record 29(1): 299-315
doi:  https://doi.org/10.3897/fr.29.183128
https://fr.pensoft.net/article/183128/


Besanosaurus leptorhynchus is an early-diverging merriamosaurian ichthyosaur from the Middle Triassic Besano Formation of Alpine Europe. When the holotype specimen was first described, potential foetal material within the specimen was identified via X-ray imaging. Now, following further preparation, we describe this material in detail. The foetal remains consist of a single, slightly disarticulated individual located in the area corresponding to the right uterine cornu in the anterior trunk region. Much of the cranium, postcranial axial skeleton and part of the appendicular skeleton are preserved. The foetus is oriented in a manner suggesting tail-first birth, a trait common in more derived ichthyosaurs. Its developmental stage corresponds to the latest prenatal stage (stage 4) established for the parvipelvian ichthyosaur Stenopterygius. Several cranial elements demonstrate features influenced by ontogeny, such as the shape of the paracoronoid process of the surangular and the curvature of the jugal. A peculiar feature of the foetus is the presence of palatine teeth, previously reported among ichthyosauromorphs only in early-diverging ichthyosauriforms and the poorly known, small-bodied ichthyosaur Wimanius, which co-occurs with Besanosaurus at Monte San Giorgio. Our observations on the foetus confirm the original interpretation of this material as foetal rather than stomach contents, as has been more recently proposed. The new data allow us to discuss observations on the in utero carrying position of ichthyosaur foetuses more broadly.

=====

Free pdf:

Spencer K Pevsner, Roger B. J. Benson & Christian F. Kammerer (2026)
A new skeleton of the gorgonopsian Aelurognathus tigriceps from the Daptocephalus Assemblage Zone (Karoo Basin, South Africa) with novel insights into the pelvic girdle, hind limbs, and tail
bioRxiv 2026.05.27.727204 (preprint)
doi: https://doi.org/10.64898/2026.05.27.727204
https://www.biorxiv.org/content/10.64898/2026.05.27.727204v1


Gorgonopsian therapsids represent a transitional condition in the evolution of synapsid locomotion and postcranial structure. Most descriptions of gorgonopsians have focused on cranial material, however, limiting their usefulness for informing patterns of postcranial evolution on the mammal stem. While some recent work has begun to focus on postcrania, especially the pectoral girdle and forelimbs, comparatively little data are available on the pelvic girdle, hind limbs and tail. We report a new specimen of the late Permian gorgonopsian Aelurognathus tigriceps comprising a partial skull and well-preserved postcranial skeleton, including the near-complete series of dorsal vertebrae and ribs, complete pelvic girdle, hind limbs, feet, and a nearly complete tail. The tail is longer than any other published gorgonopsian. The new material presented here provides an opportunity to better establish broader patterns of morphology in the gorgonopsian postcranial skeleton.

=====