Crocs' climate clock: Ancient distribution of Crocs could reveal more about past climates

Date:  June 19, 2019

Source:  Taylor & Francis Group

Underneath their tough exteriors, some crocodilians have a sensitive side that scientists could use to shine light on our ancient climate, according to new findings published in the Journal of Vertebrate Paleontology.

The idea of a clock inside a crocodile was imagined by JM Barrie in the story of Peter Pan, but instead of telling the current time, ancient crocodilians could serve as climate "clocks" -- proxies to study past climates, in a similar way to the use of tree rings and ice cores.

This is possible because scientists have discovered that some species of crocodilian were sensitive to changes in climate while others were more tolerant. Mapping the distribution of these different species using fossil remains could reveal more precise details about what the global climate was like in different locations millions of years ago.

"Our analysis suggests that crocodilians are even less of a homogenous group than previously thought and that some alligator-like reptiles were particularly good at tolerating the dramatic changes in climate that marked the end of the Eocene epoch and the beginning of the Oligocene," says lead author Dr Stéphane Jouve from the University of Sorbonne.

Continued

Cretaceous croc had steamy past – via Herp Digest

Article from University of Queensland, Australia, 3/28/18

Contacts-Media: Dr Caitlin Syme, caitlin.syme@uqconnect.edu.au, @taphovenatrix, +61 (0)428 642 061; Dr Steven Salisbury, @implexidens, s.salisbury@uq.edu.au, +61 (0)407 788 660.

An artist’s rendering of Isisfordia duncani. Credit: Matt Herne.

March 28, 2018

The death, decay and burial of an ancient extinct crocodilian from outback Queensland has revealed more about Cretaceous Period landscapes in Australia.

Scientists from The University of Queensland have completed a forensic-style investigation into fossils of the Isisfordia duncani, and found the diminutive crocodilians lived and died in brackish-water deltas.

School of Biological Sciences Dr Caitlin Syme said it was already known that the crocodile carcasses eventually ended up in the deltas, but it was uncertain if they had lived in the delta or drifted in after death.

“A decaying animal carcass can swell or bloat, and if it is washed into a lake or river, it can float and drift along in river currents,” Dr Syme said.

“If this is what happened to individuals of Isisfordia duncani, then it is possible they were already dead by the time their carcasses drifted in to the delta.”

Dr Syme compared the crocodilian fossils to modern animal carcasses and used the science of taphonomy—the study of death, decay, burial, and preservation of animal and plant remains—to predict the movement of the carcasses before they were fossilised.

“We counted which fossil bones and how many were present, whether they were still joined together as they would be in life, and whether they were scratched or broken,” she said.

“When a carcass floats in water, it will continue to decay, and parts of the skeleton will detach and sink.

“With carcasses of modern animals, for instance, the head is often the first part of the body that falls off.

“Where a fossil specimen comprises isolated and broken leg and hip bones, it indicates that the carcass probably drifted for quite a while before parts of it sunk and were eventually buried.”

Although some Isisfordia duncani fossils were incomplete, researchers found two with a large proportion of their bones still connected and intact, indicating the crocodile died near to where they lived.

“Both juvenile and adult crocodilian fossils are found at this site, which also suggests that these crocodilians were breeding in or near to these ancient deltas,” Dr Syme said.

Dr Steven Salisbury said the findings were significant because they suggested that the central-western Queensland Cretaceous Period climate was warm and wet enough for the cold-blooded reptiles to live and breed.

“The results of this study greatly improve our understanding of this part of outback Queensland during the Age of Dinosaurs, and provides valuable information on the life and times of the one of the world’s first modern crocodilians,” Dr Salisbury said.

Fossils of Isisfordia duncani were first found by a local grazier, Ian Duncan, near the outback Queensland town of Isisford in the mid-1990s.

The species was named in 2006 and the Cretaceous crocodilian is considered to be close to the ancestry of all modern crocodilians: true crocodiles, alligators and caimans, and the Indian gharial.

Seven individual Isisfordia duncani have been found, making it the best-represented Cretaceous crocodilian in Australia.

The study is published in the Royal Society Open Science journal.

Fossils and dioramas of Isisfordia duncani are on display at the Outer Barcoo Interpretation Centre and at the Queensland Museum.

New Measurement of Crocodilian Nerves Could Help Scientists Understand Ancient Animals

Apr. 4, 2013 — Crocodilians have nerves on their faces that are so sensitive, they can detect a change in a pond when a single drop hits the water surface several feet away. Alligators and crocodiles use these "invisible whiskers" to detect prey when hunting. Now, a new study from the University of Missouri has measured the nerves responsible for this function, which will help biologists understand how today's animals, as well as dinosaurs and crocodiles that lived millions of years ago, interact with the environment around them.

"The trigeminal nerve is the nerve responsible for detection of sensations of the face," said Casey Holliday, assistant professor of anatomy in the MU School of Medicine. "While we've known about these sensitive nerves in crocodiles, we've never measured the size of the nerve bundle, or ganglion, in their skulls, until now. When compared to humans, this trigeminal nerve in crocodiles is huge."

The key to this measurement is a specific hole in the skull. The trigeminal nerve is rooted inside the skull, but must travel through a large hole before it branches out to reach the crocodile's skin on its face. By examining how the skull size, brain size and ganglion size relate to each other, scientists can estimate how sensitive the face is. Eventually, Holliday hopes to measure this nerve in other ancient and contemporary species to learn more about animal behavior.

"Currently, we rely on alligators, crocodiles and birds to provide us with information about how ancient reptiles, such as pre-historic crocodiles and dinosaurs, functioned," said Holliday, who co-authored the study with doctoral student Ian George. "However, the first thing we have to do is to understand how the living animals function."

Continued:  http://www.sciencedaily.com/releases/2013/04/130404152623.htm