EVOLUTION - THE TRANSITIONAL FOSSILS
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batrachians

Introduction

The batrachian crown group (clade Batrachia, class Amphibia) comprises the Anura (frogs and toads) and the Caudata (salamanders and newts):
Picture
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).

​The crown group

The crown-Batrachia appeared when the stem lines of the anurans  and the caudates separated from one another:
Picture
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 
  • Home
  • Introduction
  • Time scale
  • Evolution of life
    • Overview
    • Eukaryotes
    • Animals >
      • Vertebrates >
        • Jawless vertebrates
        • Sharks, skates and rays
        • Chimaeras
        • Bichirs and reedfish
        • Sturgeons and paddlefishes
        • Teleostei
        • Holostei
        • Coelacanths
        • Tetrapods >
          • Eutheria
          • Metatheria
          • Prototheria
          • Squamata
          • Rhynchocephalia
          • Neognathae
          • Palaeognathae
          • Crocodylia
          • Testudines
          • Anura
          • Caudata
          • Gymnophiona
        • Dipnoi
    • Land plants >
      • Bryophytes
      • Lycophytes
      • Ferns
      • Gymnosperms
      • Angiosperms
    • References
    • Glossary
  • Data
  • About the author
  • Contact