Published on January 25th, 2023 | by David Marshall
Episode 151/152: Lissamphibian Origins
Caecilians, sometimes known as ‘blind worms’, are a lesser-known group of lissamphibians (all living amphibians). Most modern caecilians are all fossorial (burrowing) and are restricted to the moist soils and leaf litter of tropical forests. Adaptation to this specific ecology has led to radical modification of their bodies, from fusion of the bones in the head and the function of the jaw, to the loss of limbs and development of unique sensory organs.
The fossil record of caecilians is incredibly poor, with only 10 specimens available for researchers to piece together their evolutionary history with. This is further problematic because without a firm understanding of caecilian evolution, we can’t understand the origins of lissamphibians, which includes the ecologically significant groups of frogs and salamanders.
Published in Nature today, a new study led by Ben Kligman, Petrified Forest National Park and Virginia Tech, details numerous specimens of a new fossil caecilian. Discovered within a Triassic deposit, Funcusvermis gilmorei is not only the oldest known caecilian, but it also displays a unique combination of anatomical characteristics that helps illuminate the evolutionary origins of caecilians and all lissamphibians.
Whilst this discovery goes some way to answer some of the bigger questions, other problems that are raised, most notably why there is such an over-representation of Funcusvermis‘s lower right jaw.
Their morphology (physical form) isn’t the only adaptation to this ecology, strategies such as the young possessing teeth specifically for feeding off of their mother’s flesh is another, particularly gruesome but evidently beneficial, example.