Palæos:		Unit 190: Reptilomorpha
The Vertebrates		300: Batrachosauria

Reptilomorpha: Batrachosauria

Seymouriamorphs

TETRAPODA
|--TEMNOSPONDYLI
`--+--LEPOSPONDYLI
   `--Reptilomorpha
      |--Anthracosauroidea
      |  |--Gephyrostegidae
      |  `--Embolomeri
      `--Batrachosauria
         |--Seymouriamorpha
         |  |--Discosauriscus
         |  `--Kotlassiidae
         `--Cotylosauria
            |--Diadectomorpha
            `--Amniota
               |--Sauropsida
               |  |--ANAPSIDA
               |  `--EUREPTILIA 
               `--SYNAPSIDA

1. Batrachosauria

2. Discosauriscus X

3. Kotlassiidae X

4. Seymouriamorpha X

Descriptions

Batrachosauria: Seymouria + Jane Seymour

Range: from the Carboniferous

Phylogeny: Reptilomorpha : Anthracosauroidea + *: Seymouriamorpha + Cotylosauria. 

Characters: Intercentrum reduced, large canine-like maxillary tooth. 

Links: A Batrachosauroid from the late Cretaceous of France; Untitled Document; Abstracts for PaleoBios 16(4). ATW021125.

Seymouriamorpha: Ariekanerpeton, Seymouria. 

Range: Early Permian to Late Permian of Europe, Russia, Central Asia & North America.

Phylogeny: Batrachosauria : Cotylosauria + * : Discosauriscus + Kotlassiidae. 

Characters: long ventrally bent process of tabular?; posttemporal fenestrae small; slender stapes; otic tube composed of opisthotic, prootic, & parasphenoid; palate closed, without interpterygoid vacuities; pterygoid with large, transverse dorsal flange extending to skull roof (= epipterygoid?); trunk short (24-28 presacral vertebrae); vertebrae composed of large, cylindrical pleurocentrum & small, crescentic intercentrum; atlantal vertebra with paired pleurocentra & arches; neural arches "swollen" (strongly convex dorsally, in anterior or posterior view); 1, sometimes 2 sacrals; caudal hemal arches; ribs present from 1st cervical to proximal caudals; pectoral region ribs expanded; limbs stout; pectoral girdle with interclavicle, clavicles and cleithra; robust humerus & femur; phalangeal formula in manus 23443 or 23453, in pes 23453; dermal cranial bones of adults deeply sculptured, with hexagonal pattern of ridges also found in many temnospondyls (suggests skin tightly attached to skull); larvae with external gills known; lateral line present in juvenile specimens, possibly also ampullary electroreceptors.  

Image: Seymouria adapted from Clack (2002)

Note: Juveniles were aquatic, adults terrestrial.    

Links: Seymouriamorpha; Seymouria; First record of Seymouria from Early Permian fissure fills at Richards Spur, Oklahoma; Untitled Document; The Journal of Vertebrate Paleontology; The Journal of Vertebrate Paleontology; Seymouriamorpha; Utegenia shpinari; Abstracts for PaleoBios 17(1-4); Amniote origins?; Redescription of Seymouria sanjuanensis (Seymouriamorpha) from ... (abstract);  NRC Research Press- Canadian Journal of Earth Sciences. 

References: Clack (2002).  ATW031014

Discosauriscus: 

Range: Late Permian of Europe & China. 

Phylogeny: Seymouriamorpha : Kotlassiidae + *. 

Characters: skull less ossified than in Seymouria; snout shortened, kinetic line absent; rectangular tabular process (= tabular horn?); jugal exposed on ventral margin of skull; suborbital fenestra present; postorbital may contact supratemporal; "Many specimens have subdivided or fused skull roof bones"; quadrate and articular unossified; narrow interpterygoid vacuities in some; transverse flange of pterygoid may project ventrally below margin of skull; small Meckelian fenestrae present on medial face of jaw; 3 coronoids, all with teeth; dentary with up to 43 teeth; labyrinthodont dentition in more mature forms; 1-4 palatal tusks per vomer & 1-5 on palatines; 24 presacral vertebrae; 1 sacral with massive rib; gastralia absent; pectoral girdle with interclavicle bearing long parasternal process; paired clavicles with broad lateral plates; cleithra slender & cylindrical; scapula with stout supraglenoid buttress & large supraglenoid foramen; coracoid with distinct coracoid foramen; phalangeal formula is 2-3-4-5-3 for manus and pes; lateral line well preserved; ampullary electroreceptive organs present; integument of rounded scales with concentric rings.

Image: from Chordata (former site: http://home.t-online.de/home/0403906146-0002/fosswt.htm).

Note: Similar to Seymouria, perhaps less terrestrial. It has been repeatedly suggested that Discosauriscus is simply a larval form of Seymouria.  This appears not to be correct, but it is true that many reported "discosauriscids" are juvenile forms.

Links: Discosauriscus; Discosauriscus sp.; Synonyms of Discosauriscus austriacus; ?????????? ?????? (Japanese); Paleontology and Geology Glossary: Di; The Journal of Vertebrate Paleontology; Mauro J. Cavalcanti Personal Page - Abstracts; http://www.fossils.ch/img/W(ReAmph)-1.jpg; PERMIANO; Muzeum vychodnich Cech v Hradci Kralove (Czech); Snapshots from the 2002 Show: Ammonoidea 2002 I.  ATW020623.

Kotlassiidae: Buzulukia, Bystrowiana, Dromotectum, Karpinskiosaurus, Kotlassia

Range: Late Permian of Russia. 

Phylogeny: Seymouriamorpha : Discosauriscus + *. 

Characters: aquatic seymouriamorph, larger than discosaurs; 1½ sacrals(!), as only one rib of anterior sacral contacts ilium; rhomboidal ventral bony scales.

Links: paleng1_2p72abs; 615921; Seymouriamorpha; Samples2.PDF; PaleoNET | Библиотека (associated fauna).  ATW031025.

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