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Akkedops, new stem saurian reptile from Permian of South Africa + tetrapods from Middle Triassic of Monte San Giorgio (free pdfs)
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Ben Creisler
Feb 28, 2025, 5:46:42 PMFeb 28
to DinosaurMa...@googlegroups.com
Ben Creisler
New reptile papers:
Akkedops bremneri gen. et sp. nov.
Ethan Dean Mooney, Diane Scott & Robert Raphael Reisz (2025)
A new stem saurian reptile from the late Permian of South Africa and insights into saurian evolution
Swiss Journal of Palaeontology 144: 10
doi: https://doi.org/10.1186/s13358-025-00351-y
https://link.springer.com/article/10.1186/s13358-025-00351-y
The evolutionary radiation of diapsid reptiles that includes all extant and most extinct reptiles is well-represented in the Mesozoic and Cenozoic fossil records, however, the earliest stages recorded in the Paleozoic Era are limited to comparatively few taxa. Consequently, the origins of Sauria, the crown-group of Diapsida, remains poorly understood and the phylogenetic positions of the few known taxa along the saurian stem are controversial. Here, we describe Akkedops bremneri sp. et gen. nov., a new early late Permian stem saurian from the Karoo of South Africa based on two skulls and show that the famous aggregation of "juvenile Youngina” SAM-PK-K7710 is also referrable to it, thereby making this one of the best-known stem saurians. The skull has a short rostrum, open lower temporal bar, large contribution of the postfrontal to the upper temporal fenestra, slender stapes, sliver-like supratemporal with a distinct lateral flange suturing to the postorbital, and lacks both postparietal and tabular bones. The saddle-shaped quadrate is rather saurian-like in being posteriorly emarginated with a tympanic crest and unique medial flange. The post cranial skeleton of Akkedops bremneri is lizard-like and notably shows a hook-shaped fifth metatarsal and thyroid fenestra. Phylogenetic analysis recovers Akkedops bremneri as sister to Sauria, which is especially surprising considering its rather small size and slender, lizard-like morphology prior to the split between the apparently similar lepidosauromorphs and many of the comparatively robust archosauromorph saurians. Our analysis also indicates that Youngina capensis falls outside the clade of Akkedops bremenri + Sauria and does not appear to form a clade with other “younginiform” reptiles. The available evidence indicates a surprising level of complexity related to the evolution of stem saurians and the origin of Sauria that occurred in the shadow of other Paleozoic amniotes.
Ethan Dean Mooney, Diane Scott & Robert Raphael Reisz (2025)
A new stem saurian reptile from the late Permian of South Africa and insights into saurian evolution
Swiss Journal of Palaeontology 144: 10
doi: https://doi.org/10.1186/s13358-025-00351-y
https://link.springer.com/article/10.1186/s13358-025-00351-y
The evolutionary radiation of diapsid reptiles that includes all extant and most extinct reptiles is well-represented in the Mesozoic and Cenozoic fossil records, however, the earliest stages recorded in the Paleozoic Era are limited to comparatively few taxa. Consequently, the origins of Sauria, the crown-group of Diapsida, remains poorly understood and the phylogenetic positions of the few known taxa along the saurian stem are controversial. Here, we describe Akkedops bremneri sp. et gen. nov., a new early late Permian stem saurian from the Karoo of South Africa based on two skulls and show that the famous aggregation of "juvenile Youngina” SAM-PK-K7710 is also referrable to it, thereby making this one of the best-known stem saurians. The skull has a short rostrum, open lower temporal bar, large contribution of the postfrontal to the upper temporal fenestra, slender stapes, sliver-like supratemporal with a distinct lateral flange suturing to the postorbital, and lacks both postparietal and tabular bones. The saddle-shaped quadrate is rather saurian-like in being posteriorly emarginated with a tympanic crest and unique medial flange. The post cranial skeleton of Akkedops bremneri is lizard-like and notably shows a hook-shaped fifth metatarsal and thyroid fenestra. Phylogenetic analysis recovers Akkedops bremneri as sister to Sauria, which is especially surprising considering its rather small size and slender, lizard-like morphology prior to the split between the apparently similar lepidosauromorphs and many of the comparatively robust archosauromorph saurians. Our analysis also indicates that Youngina capensis falls outside the clade of Akkedops bremenri + Sauria and does not appear to form a clade with other “younginiform” reptiles. The available evidence indicates a surprising level of complexity related to the evolution of stem saurians and the origin of Sauria that occurred in the shadow of other Paleozoic amniotes.
==
Free pdf:
Silvio Renesto & Fabio Magnani (2025)
Tetrapod remains from the Ladinian (Middle Triassic) Sceltrich Beds of Monte San Giorgio UNESCO site
Rivista Italiana di Paleontologia e Stratigrafia 131(1): 201-212
DOI: https://doi.org/10.54103/2039-4942/27087
https://riviste.unimi.it/index.php/RIPS/article/view/27087
The Sceltrich beds at the base of the upper Meride Limestone (Ladinian) above the Cassina beds, yielded a rich and diversified fish fauna comprising several specimens of the predatory fish Saurichthys and sarcopterygians. Reptile findings instead are scarce and limited to few disarticulated teeth and bones, however, their descrip-tion can give an, albeit limited, insight about the reptile fauna of the Sceltrich beds which was never documented before, testifying the presence of large to mid-sized eusauropterygians and of the terrestrial tanystropheid Macrocnemus. The results indicate that the composition of the tetrapod fauna of the Sceltrich beds is similar to that of the upper levels of the Cassina beds. The taphonomic conditions that led to preservation as isolated remains could be due to a combination of different factors most probably involving a disarticulation and loss of elements during a floating phase. However it cannot be excluded that at least in some cases a residence phase of the carcass occurred for enough time to allow decomposition of soft parts, leading to disarticulation and removal of isolated elements by currents.
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