Crassigyrinus and Ventastega

Ventastega curonica (Ahlberg et al. 2008 Frasnian, Late Devonian ~365 mya; ~1m length, 20 cm skull) was derived from a sister to Ichthyostega and was sister to Crassigyrinus and less closely related to Pederpes and Whatcheeria. Although limbs were not found, the pectoral and pelvic girdles are those of limbed tetrapods. The maxilla was probably convex to match the dorsally concave mandile and, based on the scale bars,the skull might have been slightly shorter than the mandibles. Note the elongate median fontanelle between the nasals that is also found in Crassigyrinus.

Crassigyrinus scoticus (Watson 1926, Clack 1998; 2m in length; Early Carboniferous, Viséan, 340 mya) has been described as taxonomically enigmatic (see below). Wikipedia has more on its history of discovery and taxonomy. The large reptile tree (LRT) nests it clearly and robustly with Ventastega.

This aquatic tetrapod had tiny limbs and likely a long deep tail. The palate has been described as 'very fish-like'. The vertebrae were not well ossified with no sign of posterior facets to unite them. The postfrontals contacted each other medially, separating the frontals from the parietals. The skull was relatively tall on this active predator with large teeth. The basioccipital is not developed into a formed occipital condyle, but then the neck is so short that the pectoral girdle starts beneath the lateral skull bones.

Crassigyrinus closest relatives incuding Ventastega

Ahlberg PE, Clack JA, Lucsevics E, Blom H andand Zupins I 2008. Ventastega curonica and the origin of tetrapod morphology. Nature. 453 (7199): 1199–1204.

Ahlberg PE and Milner AR 1994. The origin and early diversification of tetrapods. Nature 368, 507-514.

Clack JA 1998. The Scottish Carboniferous tetrapod Crassigyrinus scoticus (Lydekker) – cranial anatomy and relationships. Transactions of the Royal Society of Edinburgh: Earth Sciences 88, 127-142.

Clack JA 2002. Gaining Ground: The origin and evolution of tetrapods. Indiana University Press.

Herbst EC and Hutchinson JR 2018. New insights into the morphology of the Carboniferous tetrapod Crassigyrinus scoticus from computed tomography. Earth and Environmentsal Science Transactions of the Royal Society of Edinburgh 1–19.

Panchen AL 1985. On the amphibian Crassigyrinus scoticus Watson from the Carboniferous of Scotland. Philosophical Transactions of the Royal Society of London B 309: 505-568.

Panchen AL 1990. The pelvic girdle and hind limb of Crassigyrinus scoticus (Lydekker) from the Scottish Carboniferous and the origin of the tetrapod pelvic skeleton. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 81(1):

Panchen AL 1991. The early tetrapods: classification and the shapes of cladograms in: Origins of the Higher Groups of Tetrapods: Controversy and Consensus. Eds. Schultze HP and Trueb L. Comstock Publishing Associates, Cornell University Press, Ithaca and London.

Porro LB, Rayfield EJ and Clack JA 2023. Computed tomography and three-dimensional
reconstruction of the skull of the stem tetrapod Crassigyrinus scoticus Watson, 1929. Journal Vertebrate Paleontology https://doi.org/10.1080/02724634.2023.2183134

Watson DMS 1926. Croonian Lecture – The evolution and origin of the Amphibia. Philosophical Transactions of the Royal Society B 214:189–257.

wiki/Crassigyrinus
wiki/Ventastega

Stegocephalia

Greererpeton

Pederpes - Whatcheeria

Crassigyrinus

Eoherpeton

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