The largest amphibians of all time

Yesterday we looked at Siderops, a big plagiosaur and peeked at Koolasuchus, a giant plagiosaur. That makes today a good today to review the largest amphibians of all time (Fig. 1, click to enlarge).

Figure 1. Click to enlarge. The largest amphibians of all time include Mastodonsaurus, Prionosuchus, Koolasuchus, Siderops, Crassigyrinus and the extant Andrias, the giant Chinese salamander.

Figure 1. The cover of Giants, the book that launched my adult interest in dinosaurs, pterosaurs and everything inbetween.

Figure 2. The cover of Giants, the book that launched my adult interest in dinosaurs, pterosaurs and everything inbetween.

Back in 1989
and eager to locate the largest amphibian of all time, I added Prionosuchus (Fig. 1) to the popular natural history book, “Giants of Land, Sea and Air – Past and Present” (Fig. 2). Since the largest Prionosuchus is only known from fragments and slivers, much had to be restored using phylogenetic bracketing.

Now
Mastodonsaurus is probably just as long, but much bulkier, making it the largest amphibian of all time. It was the size of a Hippopotamus (Fig. 3).

The largest living amphibian is Andrias, the Chinese salamander.

Mastodonsaurus jaegeri (Jaeger 1828; Schoch 1999; Middle Triassic; skull length 1.2m; overall length 6m) is the largest lepospondyl in the LRT. Traditionally it was considered a temnospondyl, but if so that would make all amniotes temnospondyls, too, which was not the intention of the definition. Anterior dentary tusks fit through new skull openings (in red above) anterior to the nares. Intercostal plates overlapped succeeding ribs. Mastodonsaurusinhabited swampy ponds.

Andrias davidianus (Blanchard 1871; 1.8m in length; extant) the Chinese giant salamander, is a sister to Rana, the bullfrog and derived from a sister to Gerobatrachus.

Figure 1. Living hippopotamus. Now I ask you, does this look like a relative to deer and giraffes? Or to mesonychids?

Figure 3. Living hippopotamus, an amphibious mammal related to Mesonyx.

References
Blanchard É 1871.Note sur une nouvelle Salamandre gigantesque (Sieboldia Davidiana Blanch.) de la Chine occidentale. Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences. Paris 73: 79.
Jaeger GF 1828. 
Über die fossile Reptilien, welche in Württemberg aufgefunden worden sind. 48 pp., 6 pls.; Stuttgart (Metzler).
Schoch RR 1999. 
Comparative osteology of Mastodonsaurus giganteus (Jaeger, 1828) from the Middle Triassic (Lettenkeuper: Longobardian) of Germany (Baden-Württemberg, Bayern, Thüringen). Stuttgarter Beiträge zur Naturkunde Serie B. 278: 1–175. PDF

wiki/Mastodonsaurus
wiki/Andrias

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