Reptiliomorpha: Embolomeri

Taxa on This Page

1. Diplovertebron X
2. Embolomeri X
3. Eogyrinidae X
4. Pholiderpeton X
5. Pholidogaster X
6. Proterogyrinus X

Archeria crassidiscus (Cope, 1884), Eogyrinidae Early Permian of Texas,
life reconstruction, by Arthur Weasley (Larger image (Wikimedia))

Descriptions

Embolomeri: Archeria, Pholiderpeton, Proterogyrinus.

Image: Proterogyrinus scheeleri from Holmes 1984).

Note: see figure and note under Anthracosauroidea.

Links: Phylogenetic position of the Embolomeri; Biology 356; Phylogeny of stegocephalians; Embolomeri.

References: Clack (2002) [C02]. ATW020128.

Proterogyrinus: P. pancheni Smithson 1986; P. scheeleri Romer 1970.

Range: Early Carboniferous of North America & Europe (Scotland).

Phylogeny: Embolomeri :: Pholidogaster+ *.

Characters: kinetic line present; neck short; 32 presacral vertebrae; vertebrae not fully embolomerous (see figure at Anthracosauroidea); tail laterally flattened; phalangeal formula 23453;

Note: [1] Proterogyrinus was a primitive semi-aquatic embolomere able to manage well both on land and in the water. It had well-developed limbs and a short neck and relatively short trunk, with 32 presacral vertebrae. The tail is flattened to aid in swimming. As with lobe-fined fish (osteolepiforms), there is a line of weakness between the skull table (the flat area at the back of the skull) and the cheek area, which allowed the skull to flex during jaw-opening. A notch at the back of the skull may have contained an eardrum, but the large bladelike stapes of  primitive anthracosaurs are quite different to the narrow rod-like structure of animals with an ear adapted to detected sound in air. P. pancheni is the Scottish form, known from both the  Dora Bone Bed near Cowdenbeath, Fife and the Lothian Region. P. scheeleri (see figure above, at Embolomeri) was recovered from the Bickett Shale, Bluefield Formation from Greer, West Virginia, USA. Both are of Serpukhovian age, although the American form is somewhat older. MAK981010. [2] note the still somewhat fish-like tail in the figure at Embolomeri. Clack 2002) compares this structure to Eusthenepteron and Acanthostega to make the argument that the transformation proceeded from anterior to posterior -- hox order. However, the argument is at least as strong that the transformation proceeded from distal to proximal (BMP or Shh order?). ATW020621

Images: Top: Proterogyrinus pancheni life reconstruction by Mike Coates, Right. Proterogyrinus scheeleri by David Peters, Reptile evolution MAK111107

Links: Transitional Vertebrate Fossils FAQ: Part 1B; Historický vývoj (Czech). ATW020621.

Pholidogaster: P. pisciformes Huxley.

Range: Early Carboniferous (late Visean to early Serpukhovian) of Scotland (Ironstone at Gilmerton, near Edinburugh) Euramerica

Phylogeny: Embolomeri :: Proterogyrinus + *.

Size Adult Length over 1 metre long

Comments: Trunk very long and slender, the limbs are small and feeble. The pectoral arch apparently far back. There is a strong ventral (belly) armour of scutes.

Eogyrinidae: Palaeoherpeton, Pteroplax

Range: Late Carboniferous to Middle Permian of Europe & North America.

Phylogeny: Embolomeri : (Proterogyrinus+ Pholidogaster) + * : Diplovertebron + Pholiderpeton.

Image: Diplovertebron (~60 cm).

Note: The eogyrinids were one of a number of lineages of relatively large, long-bodied tetrapods that frequented late Carboniferous rivers and watercourses. MAK981014.

Links: Class:Amphibia. ATW020621.

Pteroplax cornutus Hancock and Atthby 1868, life reconstruction, by Dmitry Bogdanov . Wikipedia, GNU Free Documentation/Creative Commons Attribution

Diplovertebron: D. punctatum Fritsch 1885

Range: Late Carboniferous (Moscovian? Bashkirian?) of Europe & North America.

Phylogeny: Eogyrinidae : Pholiderpeton + *.

Image: a rather imaginative reconstruction from Une page Web sur la période jurassique / A web page about jurassic period.

Links: Yale Peabody Museum: The Mural, Carboniferous & Devonian; Old, old reasons for hatred; Carbonifero Italian); La galerie de la page jurassique : la faune aquatique et terrestre (French); ERA PALEOZÓICA (Spanish). ATW020621.

Pholiderpeton: = Eogyrinus) P. atheyi Watson 1926, P scutigerum Huxley ??

Range:  Late Carboniferous (Bashkirian [Westphalian B])

Phylogeny: Eogyrinidae : Diplovertebron + *.

Characters: ~200 cm; skull roof and palate only weakly attached [C02]; massive stapes [C02]; both pleurocentrum and intercentrum complete cylinders; anocleithrum present [C02].

Image: Pholiderpeton, (A) skull in dorsal view; (B) in palatal view; and (C) life reconstruction, from [C02], with (C) modified to show elements of internal skeletal features.

Links: Class-Amphibia

References: Clack (2002) [C02]. ATW030414.