Meet ‘Fiona’ the Pregnant Ichthyosaur, Chile’s Oldest Marine Reptile Mother

In the shadow of a huge glacier in Patagonia, paleontologists have unearthed a rare fossil: an ancient marine reptile that died during pregnancy. This dolphin-like creature, called an ichthyosaur, is the first of its kind to be discovered in Chile, where it was recovered from an excavation site near Tyndall Glacier in the Southern Patagonian Ice Field.

“This site is really unique because it captures a time in Earth’s history when we don’t have a very good fossil record for marine reptiles,” said Erin Maxwell, ichthyosaur specialist and curator of marine reptiles at the State Museum of Natural History. in Stuttgart, Germany, who helped dig up the fossil, Live Science told Live Science.

Ichthyosaurs (which translate to “fish lizards”) dominated the seas from the early Triassic period around 251 million years ago, and they lived alongside the dinosaurs until about 95 million years ago, according to the University of California, Berkeley (opens in a new tab). These fearsome marine reptiles mainly ate ancient, hard-shelled squid, as well as some types of smaller fish and ichthyosaurs. The smallest species of ichthyosaur grew to be about 1.3 feet (0.4 meters) long, while the largest grew to nearly 69 feet (21 meters) from snout to tail, according to (opens in a new tab)National geographic (opens in a new tab).

At 13 feet (4 meters) long, Tyndall’s ichthyosaur is a medium-sized specimen that dates to around 129 to 139 million years ago, during the early Cretaceous period (around 145 at 66 million years).

Related: Slideshow: Ancient Sea Monsters

The fossil caught Maxwell’s attention when it was first discovered in 2009 by paleontologist Judith Pardo-Pérez, who joined Maxwell’s research group in Stuttgart shortly after the fossil was discovered. Pardo-Pérez – now a researcher at the GAIA Antarctic Research Center at the University of Magallanes (UMAG) in Punta Arenas, Chile – and her colleagues who found the ichthyosaur specimen nicknamed it “Fiona” after the actress Cameron Diaz’s ogre character in the film “Shrek” (Dreamworks, 2001), because the fossil’s preservative oxide coating turned it green, like its brave ogre namesake.

But it took scientists 13 years to finally excavate and study Fiona’s remains, which Maxwell says is not uncommon.

A helicopter prepares to lift the heavy load of ichthyosaurs, in front of the Tyndall glacier. (Image credit: Alejandra Zúñiga)

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“There is often a very large lag between the discovery of the fossil and the study of the fossil,” Maxwell explained. In this case, the delay was partly due to location: Tyndall Glacier is extremely remote, and so every fossil at the site – including 23 other ichthyosaurs that were discovered alongside Fiona – had to be carefully airlifted by helicopter after the excavations. Unfortunately, many more fossils were left behind. “We have nearly a hundred ichthyosaurs in the Tyndall Glacier fossil bed and many of them, unfortunately, will never be excavated, due to the difficulty of access, the fact that they are in risk areas (cliff edge) and lack of funds,” Pardo-Pérez said. said in a statement (opens in a new tab).

Specimens like Fiona, who fossilized during pregnancy, are particularly useful for paleontologists because they offer insight into the multiple stages of this species’ life cycle. “We can say, for example, how many embryos these species might have had and how big they were at birth,” Maxwell said. The first known pregnant ichthyosaur fossil, discovered in 1749 and scientifically described in 1842, confirmed that ichthyosaurs produce live young rather than lay eggs like most modern reptiles do, she added.

Maxwell hopes the discovery will help spark enthusiasm for South American paleontology, which has historically been overlooked in favor of North American, Russian, Chinese and Western European sites. “We really only have a picture of what is happening in half the globe for the Mesozoic [252 million to 66 million years ago]”, she said. “So these findings are very, very important in helping to bring a holistic perspective to our understanding of the Cretaceous oceans.”

Originally posted on Live Science.

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