Andrew R. Milner

The earliest known Salamanders (Amphibia, Caudata):A record from the Middle Jurassic of England

Abstract Marmorerpeton gen. nov. represented by M. kermackisp. nov. and M. freemani sp. nov., is the earliest known genus of fossil salamander from the Upper Bathonian, Middle Jurassic of Kirtlington, Oxfordshire, England. Marmorerpeton is more primitive than any other known salamander in the absence of intravertebral spinal nerve foramina in the atlantal centrum, but in other features it resembles members of the family Scapherpetontidae, neotenous salamanders otherwise known from the Upper Cretaceous and Palaeocene. The Kirtlington herpetofauna is a unique freshwater assemblage of Middle Jurassic small amphibians and reptiles, several of which represent the earliest known occurrences of their respective groups.

Frogs and salamanders from the Upper Jurassic Morrison Formation (Quarry Nine, Como Bluff) of North America

ABSTRACT Previously undescribed frog and salamander bones from the Morrison Formation, at Quarry Nine, Como Bluff, Wyoming, are reported. One anuran ilium is diagnostically discoglossid and forms the basis of Enneabatrachus hechti, gen. et sp. nov. A second ilium is diagnostically pelobatid and is the earliest record for the family Pelobatidae, although it is indeterminate below family level. Salamander vertebrae appear to represent two morphological types but neither can be diagnosed critically. The previously described anuran taxa Eobatrachus agilis Marsh and Comobatrachus aenigmatis Hecht and Estes and the salamander Comonecturoides marshi Hecht and Estes are all based on non-determinate elements and must be considered nomina dubia at our present state of knowledge.

Early tetrapod evolution

Tetrapods include the only fully terrestrial vertebrates, but they also include many amphibious, aquatic and flying groups. They occupy the highest levels of the food chain on land and in aquatic environments. Tetrapod evolution has generated great interest, but the earliest phases of their history are poorly understood. Recent studies have questioned long-accepted hypotheses about the origin of the pentadactyl limb, the phylogeny of tetrapods and the environment in which the first tetrapods lived.

SLAUGENHOPIA TEXENSIS (AMPHIBIA: TEMNOSPONDYLI) FROM THE PERMIAN OF TEXAS IS A PRIMITIVE TUPILAKOSAURID

Abstract The temnospondyl amphibian Slaugenhopia texensis from the late Leonardian (Early Permian) San Angelo Formation of Knox County, north-central Texas, was described as a trimerorhachid by Olson. Restudy of the material shows it to be a member of the Tupilakosauridae and thus a more derived member of the clade Dvinosauria than the trimerorhachids. It possesses derived character-states of the Tupilakosauridae, including the reduced postfrontal, the postorbital-parietal suture, and the posterior pterygoid notch, but lacks the embolomerous centra of the Triassic tupilakosaurids. It is the earliest and most primitive tupilakosaurid and extends the history of the group back to the end of the Early Permian.

The tetrapod Caerorhachis bairdi Holmes and Carroll from the Lower Carboniferous of Scotland

The tetrapod Caerorhachis bairdi, probably from the Pendleian Limestone Coal Group in the Scottish Midland Valley, is redi agnosed and redescribed, and its affinities are discussed. Caerorachis was originally interpreted as a temnospondyl amphibian, based on characters that are now regarded as primitive for tetrapods, or of uncertain polarity. Several features of Caerorhachis (e.g. gastrocentrous vertebrae, curved trunk ribs, reduced dorsal iliac blade, L-shaped tarsal intermedium) are observed in certain primitive amniotes. In particular, Caerorhachis resembles ‘anthracosaurs’, generally considered to be among the most primitive of stem-group amniotes. The phylogenetic position of Caerorhachis is considered in the light of recently published cladistic analyses of Palaeozoic tetrapods. Most analyses place Caerorhachis at the base of, or within, ‘anthra- cosaurs’. When multiple, equally parsimonious solutions are found, its ‘anthracosaur’ affinities are shown in at least some trees, and are supported by several informative and, generally, highly consistent characters. Alternative phylogenetic placements (e.g. sister taxon to temnospondyls) are usually less well corroborated. If the fundamental evolutionary split of most early tetrapods into stem-group lissamphibians (e.g. temnospondyl s) and stem-group amniotes (e.g. ‘anthracosaurs’) is accepted, then the revised interpretation of Caerorhachi s sheds light on near-ancestral conditions for Amniota.

LONGISCITULA HOUGHAE DEMAR, 1966 (AMPHIBIA: TEMNOSPONDYLI), A JUNIOR SYNONYM OF DISSOROPHUS MULTICINCTUS COPE, 1895

The Permo-Carboniferous temnospondyl amphibian families Dissorophidae and Trematopidae are each characterized by a suite of derived characters, most of which are mutually exclusive. Dissorophidae have distinctive dermal scutes and otic notch (see diagnosis below) while Trematopidae have a characteristic enlarged external naris (Dilkes, 1993; Sumida et al., 1998). A number of supposed dissorophid-trematopid intermediates have been described, but one, Actiobates peabodyi (Eaton, 1973), is now generally agreed to be a primitive trematopid (e.g., Sumida et al., 1998), while two others, Ecolsonia cutlerensis (Vaughn, 1969; Berman etl al., 1985) and Mordex calliprepes (Steen, 1938; Milner, 1986), are under study by the author and will be redescribed as basal trematopids. None of these three genera has enlarged dorsal dermal scutes. One taxon, however, has been described as possessing both the characteristic dissorophid scutes and the characteristic trematopid external nares, and this forms the subject of this revisionary note.