The earliest known specimen of
Salamandroid was found near Jianping, China within rocks that date to
approximately 157 Ma. This specimen predates the previous record of Valdotriton
in Europe by nearly 40 Ma. The split between Salamandroidea and
Chryptobranchiodea is a major event in the evolution of salamanders. Recent
molecular data suggests an early age for the split, but before this discovery
the molecular evidence could not be reconciled with the fossil record.
Beiyanerpeton Jianpingensis
The specimen described in this
paper has a snout-vent length of approximately 100mm. Its bone structure
includes short, straight ribs, a wide skull, and one set of sensory canals
leading to the nares for olfaction and another along the maxilla, presumably for
facial control (trigeminal). This animal does lack some derived Salamandroid
characteristics within the structure of the vomer and also lacks pedicellate
teeth. The authors classified this species as paedomorphic based on the
preservation of gill rakers in the large specimens. These specimens are
presumably adults.
Within the context of evolutionary history,
the data collected in this experiment suggests that palantine function for
tooth bearing occurred early in evolution for salamanders. Nonpedicellate teeth
may also be the ancestral form of tooth structure in the salamander.
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Proposed phylogeny for B. Jianpingensis
Gao K and Shubin. Late Jurassic salamandroid from
western Liaoning, China. Proceedings of the National Academy
of Sciences of the United States of America 2012.
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