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Episode 2 – Crocodilians Past and Present

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Second Episode!

Listen to Episode 2 on PodBean, Spotify, YouTube, or your podcast source of choice!

We are now on Episode 2, and once again this blog post will have some extra links and information having to do with our most recent episode.
This one was all about Crocodilians Past and Present. 

Paleo News
Here are the links to our news items for this episode.
Earliest Deuterostome
A small fossil discovered in China may be the earliest ancestor of all deuterostomes, a group including echinoderms and chordates, and therefore us. [News Report]
Dinosaur Proteins
Two recent studies provide evidence of fossilized proteins in two different dinosaur fossils, something that until recently was unheard of. [News Report]
Wolf-Sized Otter
A fossil otter, also from China, was roughly 100 lbs (the size of a modern wolf), and raises questions about otter evolution and family history. [News Report]
Australia Megafauna Extinction
A pair of studies just came out regarding the debate over whether the fossil megafauna of Australia were pushed to extinction by climate change or the appearance of humans.
The first says it was the climate. [News Report]
The next says it wasn’t. [News Release]

What are Crocodilians?

This group includes alligators, crocodiles, caimans, and the Indian gharial. There are roughly 24 extant (living) species and they are found on every continent except Europe and Antarctica. They include the largest living species of reptiles and are some of the few reptiles that still act as dominant predators in their ecosystems.

File: Crocodilia collage.jpg
Top left: saltwater crocodile; Bottom left: Indian gharial; Right: American alligator. [Image from Wikimedia Commons.]

These large aquatic reptiles all live in similar environments and have familiar body designs. All have relatively short legs, powerful tails, and long flat jaws. Though there is variety among these traits, they are all easily recognizable as relatives. But this was not always the case, with their fossil record holding some truly unique specimens.

Fossil Crocodilians

The ancestors of the modern groups of crocodilians first appear in the fossil record in the late Cretaceous about 100 million years ago. Though many resembled those that we see today, others were adapted for very different lifestyles. One extreme example is the now-extinct pristichampsids. These were hoof-toed crocodilians built for running their prey down on land.

There were also some truly colossal species that lived during and after the “Age of Reptiles”. 

Large_crocodyliformes_2015mod.png
Crocodylus porosus, the saltwater crocodile, is the largest extant crocodilian but is dwarfed by its ancient predecessors. [Modified from Wikimedia Commons.]

Crocodylomorpha and More

The larger group Crocodylomorpha includes the ancient relatives of the crocodilians and has some of the most diverse forms of croc-like animals. This group fell within the larger classification of Archosauria, a reptilian grouping that was split between the crocodilian ancestors and cousins, and those of birds and other dinosaurs.

The crocodylomorphs included marine species, plant eaters, mammal mimics, and even more terrestrial predators.

Sebecus_icaeorhinus_AMNH3160.jpg
Sebecus incaeorhinus, a terrestrial running crocodylomorph. [Specimen from the American Museum of Natural History. Photo by David.]
Mystriosarus_bollensis_AMNH5138.jpg
Mystriosaurus bollensis (skeleton), a crocodylomorph adapted for life at sea. Teleorhinus robustus (skull), an aquatic pholidosaur, cousin of the famous Super Croc. [Specimens from the American Museum of Natural History. Photo by David.]

There were even more ancient cousins of the crocodylomorphs, the very earliest ancestors of crocodilians that appeared at the beginning of the age of dinosaurs. Some of these were the dominant land predators of their time.

P1030784.JPG
Prestosuchus chiniquensis, a large terrestrial predator closely related to crocodylomorphs. [Specimen from the American Museum of Natural History. Photo by David.]

There were even animals unrelated to crocodilians that shared their body plan and lifestyle, like the phytosaurs.

P1030777.JPG
Rutiodon carolinensis, a reptile related to archosaurs with a similar body design to crocodylomorphs. [Specimen from the American Museum of Natural History. Photo by David.]

If you’re looking for more details or information about crocodilians and their family history, a fantastic book to look into is Biology and Evolution of Crocodylians by Gordon Grigg and David Kirshner. An excellent overview of the group.

The UCMP Berkeley archosaur webpage is also a great place to learn about the evolutionary history of crocs and their relatives.

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Comments

3 responses to “Episode 2 – Crocodilians Past and Present”

  1. Episode 21 – Dinosaurs, an Introduction – COMMON DESCENT Avatar
    Episode 21 – Dinosaurs, an Introduction – COMMON DESCENT

    […] – these are the traits that unite Dinosauria. They sit on the archosaur family tree, opposite crocodylomorphs and very close to […]

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  2. Paleona Avatar
    Paleona

    I was recently recommended this podcast and I love it so far! I’m looking forward to listening through the backlog while working on art. Honestly, I was sold when you said Happy Birthday to Mewtwo, haha. Thanks for mentioning Simosuchus in this episode- what a cutie!

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  3. Pat Thomas Avatar
    Pat Thomas

    First-time listener here, off the main topic, but really enjoyed the discussion on Australian megafauna extinction. The study led by Dos Santos raised some compelling points, especially around how climate change may have contributed to their extinction. But I think it’s also important to consider the role of First Nations people in shaping the environment. Practices like cool burns, evident in the geological record, promoted grasslands over dense bush, supporting hunting and sustainable land use.Interestingly, archaeological and paleoecological evidence suggests that these controlled burning practices began around the same time megafauna populations were declining. This overlap hints at a complex interplay between human land management and ecological changes.What’s really interesting is how one study suggests vegetation remained stable enough to support megafauna, while another implies otherwise. I don’t think these findings are necessarily contradictory; both can be true depending on the region. Understanding the cultural practices of the people living in these areas at the time could actually help link these theories together, showing how human activity and climate change worked in tandem to reshape ecosystems.Also worth noting: changes in carbon isotopes found in megafauna teeth may indicate shifts in plant diversity and dominant species over time. These changes could reflect not just natural climate variations, but also the long-term impact of human land management.

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