Eoherpeton watsoni (Panchen 1975) Visean, Early Carboniferous~330 mya, 1 m in length, was 8 million years older than its sister, Proterogyrinus. Both were derived from a sister to Ichthyostega and both phylogenetically preceded Eldeceeon.

Distinct from Proterogyrinus, the skull of Eoherpeton had relatively a larger naris (nostril) set higher on the skull. The orbit was more circular. The maxilla contacted the quadratojugal, a primitive trait. The otic notch (embayment at the back of the skull) was greatly reduced. The teeth were larger and fewer in number.

The rest of the skeleton is poorly known, but the pelvis was deeper, as in Ichthyostega.

A reptilomorph family tree is here. A more complete family tree of the Reptilia and their ancestors is here.

Anthracosaurus russelli (Huxley 1863, Panchen 1977, Clack 1987; Westphalian, Late Carboniferous, 310 mya, skull length 40cm) was originally considered a labyrinthodont and the wide skull recalls Tiktaalik, but here Anthracosaurus nests with Neopteroplax as a derived embolomere/anthracosaur. At least one orbit has an inverted teardrop shape/ The marginal and palatal fangs are quite large. Although flattened in dorsal view, comparisons suggest the jaw margin was convex, as in Neopteroplax. Clack 1987 reconstructed a chimaera with a narrower palate and orbits at mid skull that does not nest well within the LRT.

Neopteroplex conemaughensis (Romer 1963; Late Carboniferous, ~310 mya; 3 m in length, 40 cm skull) evolved to be similar to temnospondyls, like Eryops, but had a terminal naris and canine fangs together with nares pushed to the midline.

Clack JA 1987. Two new speciemens of Anthracosaurus (Amphibia: Anthracosauria) from the Northumberland coal measures. Palaeontology 30(1):15-26.

Huxley TH 1863. Description of Anthracosaurus russelli, a new labyrinthodont from the Lanarkshire coalfield. Quartery Journal of the Geological Society 19:56-58.

Panchen AL 1975. A new genus and species of anthracosaur amphibian from the Lower Carboniferous of Scotland and the status of Pholidogaster pisciformis Huxley. Philosophical Transactions of the Royal Society of London, B. 269: 581-640.

Panchen AL 1977. On Anthracosaurus russelli Huxley (Amphibia: Labyrinthodontia) and the family Anthracosauridae. Philosophical Transactions of the Royal Society B. 279 (968): 447–512.

Romer AS 1963.The larger embolomerous amphibians of the American Carboniferous. Bulletin of the Museum of Comparative Zoology 128(9):415-454

Ruta M, Jeffery JE and Coates MI 2003. A supertree of early tetrapods. Proc. R. Soc. Lond. B (2003) 270, 2507–2516 DOI 10.1098/rspb.2003.2524 online pdf

Smithson TR 1985. The morphology and relationships of the Carboniferous amphibian Eoherpeton watsoni Panchen. Zoological Journal of the Linnean Society 85: 317–410.
DOI: 10.1111/j.1096-3642.1985.tb01517.x

wiki/Eoherpeton
wiki/Neopteroplax
wiki/Anthracosaurus