Episode 246 – Gharials

Listen to Episode 246 on Podbean, YouTube, Spotify, or wherever you listen to your favorite podcasts!

Most living crocodilian species are overall pretty similar in their appearance, but one group really stands out with their bulging eyes and incredibly slender snouts. This episode, we investigate just what’s going on with Gharials.

In the news
Gradual loss of eyesight in hagfish
Evolution of giant heads and tiny arms in theropod dinosaurs
Proliferation of fungi around the Cretaceous mass extinction
Heron-like dinosaur might have hunted for fish

The Oddest Crocs

Modern crocodilians tend to look pretty similar overall – it’s why there are so many tips for distinguishing crocodiles from alligators, for example – but gharials stand out among them with their distinctive long, narrow snouts and small needle-like teeth.

Two living species belong to the family Gavialidae. First are Indian gharials, which possess protruding eyes and extraordinarily slender snouts, and which are also among the largest and most aquatic of living crocodilians. Second are false gharials, whose anatomy isn’t nearly as extreme, more closely resembling their crocodile cousins.

All modern crocodilian species are known to put on flashy and noisy displays, but adult male Indian gharials uniquely possess a bulbous protrusion called a ghara at the end of their snout, which is probably an important display feature and which might also aid them in creating loud “pops” by snapping their jaws shut underwater.

For a long time, crocodilian researchers were confounded by the so-called “gharial problem.” Different lines of evidence (generally genetics vs. fossils and skeletons) consistently disagreed over the position of Indian gharials in the crocodilian family tree, some placing them alongside false gharials in their own family, and others placing false gharials within crocodiles and Indian gharials as a separate branch all their own. Only in recent years have scientists finally found some agreement in the data, and the consensus of a two-species gharial family (described above) has begun to settle.

The limited diversity of modern gharials is vastly overshadowed by their fossil relatives. Several ancient species have been found all over the world at least as far back as the Early Cenozoic Era. These included freshwater and marine species, as well as some of the largest crocs in Earth history, some estimated to have grown more than ten meters (33 feet) long.

But ancient gharials aren’t the only gharial-shaped crocs in the fossil record. Long, slender snouts have evolved several times across the crocodilian extended family, and even beyond in distantly-related reptiles like phytosaurs. This widespread convergence has led to another source of scientific debate – the “longirostrine problem.” The similarity of these various crocs has made it difficult at times to distinguish “true” ancient gharials from the rest, and while these long snouts are generally viewed as an adaptation for hunting fish and other underwater prey, plenty of evidence suggests that modern and fossil species are more varied in their diets than previously recognized. All in all, long-snouted crocs are a much more diverse group than their shared anatomy would suggest.

Learn More

Indian Gharial – Smithsonian Zoo
False Gharial – Smithsonian Zoo

Gharial acoustic signaling (technical, open access)
Resolving the “gharial problem” (technical, open access)
Miocene Caribbean gharials and patterns of longirostry in crocs (technical, open access)

__

If you enjoyed this topic and want more like it, check out these related episodes:

• Episode 168 – Marine Crocs
• Episode 194 – Alligators and Caimans
• Episode 220 – Terrestrial Crocs

We also invite you to follow us on Facebook or Instagram, buy merch at our Zazzle store, join our Discord server, or consider supporting us with a one-time PayPal donation or on Patreon to get bonus recordings and other goodies!

Please feel free to contact us with comments, questions, or topic suggestions, and to rate and review us on Spotify or Apple Podcasts!