Introduction
The batrachian crown group (clade Batrachia, class Amphibia) comprises the Anura (frogs and toads) and the Caudata (salamanders and newts):
The terminal clades shown at the right-hand side of the above tree each have a separate page that can be reached through the menu bar at the top of the page (under Evolution of Life/Animals/Vertebrates/Tetrapods).
The stem group
Unfortunately, no representatives of the batrachian stem group have been documented with any degree of consensus. Anderson et al (2008) did assign Gerobatrachus hottoni to the stem-Batrachia, but a number of more recent workers (e.g Ascarrunz et al, 2016; Schoch, 2019) have placed that species in the amphibian stem group.
Another possible identification of the stem-Batrachia is with the extinct amphibian group known as the Albanerpetontidae, but more work is needed to confirm that assignment (Matsumoto and Evans, 2018).
Another possible identification of the stem-Batrachia is with the extinct amphibian group known as the Albanerpetontidae, but more work is needed to confirm that assignment (Matsumoto and Evans, 2018).
The crown group
The crown-Batrachia appeared when the stem lines of the anurans and the caudates separated from one another:
The earliest known member of the batrachian crown group is the Early Triassic Triadobatrachus massinoti, which is also the oldest known representative of the crown-Amphibia (see Amphibians section above). For completeness, this fossil is illustrated again below (click on images for larger version):
Image credits - Batrachians
- Header (Houston toad, Bufo houstonensis) By USFWS Endangered Species [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
- Triadobatrachus massinoti (in Natural History Museum, Paris) By Ghedoghedo [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons
- Triadobatrachus massinoti (Restoration by Nobu Tamura) By Nobu Tamura (http://spinops.blogspot.com) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0