US EPA

7437134 

Journal Article 

Anurans 

ten Donkelaar, HJ; , 

1998 

Springer Berlin Heidelberg 

Berlin, Heidelberg 

The Central Nervous System of Vertebrates 

1151-1314 

10.1007/978-3-642-18262-4_19 

http://link.springer.com/10.1007/978-3-642-18262-4_19
Exit
 

When they first appear in the fossil record during the Jurassic, frogs appear essentially modern in their skeletal anatomy (Romer and Parsons 1977; Carroll 1988). Frogs, caecilians and salamanders share a number of derived features that have led herpetologists to ally them in a single group, the subclass Lissamphibia (see Parsons and Williams 1963; Duellman and Trueb 1986). All these are mainly small animals that depend on cutaneous respiration, have spool-shaped vertebrae, and most members of all three orders have a peculiar, so-called pedicellate, tooth structure in which the base and crown are separated by a zone of fibrous tissue (Carroll 1988). Despite these similarities, frogs, salamanders and caecilians are very different from one another in skeletal structure and ways of life, both now and throughout their known fossil history (Freytag 1974; Heusser 1974a; Young 1981; Duellman and Trueb 1986).