Amphibian August #04 – Sclerocephalus

And now it’s time for temnospondyls!

One of the most successful tetrapod groups of the late Palaeozoic and early Mesozoic, temnospondyl amphibians first appeared 330 million years ago and flourished for the next 210 million years, being found on every continent occupying a diverse range of habitats. And, depending on who you ask, they might even still be around today in the form of modern amphibians – but we’ll talk more about that later on in the month.

Sclerocephalus lived during the Late Carboniferous of Germany (~301-297 mya), and grew to around 1.5m long (4′11″). It’s known from many well-preserved fossil specimens, some of which show soft tissue impressions and stomach contents, and we even have evidence of its complete life cycle from larvae to metamorphosis to full maturity.

Juveniles were slender-bodied with external gills and longer tails, preying on small crustaceans and plankton. As they grew and metamorphosed, they lost their gills, strengthened their skeleton, and bulked up their limbs, moving to a diet of fish and other amphibians.

Unlike modern amphibians Sclerocephalus and some other temnospondyls were also scaly, although it’s important to note that these were much more like fish scales than those of reptiles. There would have been a layer of skin over the top, and the scales probably wouldn’t have been particularly visible in life.