by In the shadow of a massive Patagonian glacier, paleontologists have unearthed a rare fossil find: an ancient marine reptile that died during pregnancy. This dolphin-like creature, called an ichthyosaur, is the first of its kind discovered in Chile, where it was recovered from an excavation at Tyndall Glacier in the Southern Patagonian Ice Field.
“This site is truly unique because it captures a time period in Earth’s history when we don’t have a very good fossil record for marine reptiles,” Erin Maxwell, an ichthyosaur specialist and curator of marine reptiles at the State Museum of Natural History in Stuttgart, Germany, who helped excavate the fossil, told Live Science.
Ichthyosaurs (which translates to “fish lizards”) dominated the seas from the Early Triassic, about 251 million years ago, and they coexisted with dinosaurs until about 95 million years ago, according to the University of California, Berkeley† These formidable marine reptiles ate mostly ancient, hard-shelled squid relatives, as well as some species of fish and smaller ichthyosaurs. The smallest ichthyosaur species grew to about 1.3 feet (0.4 meters) long, while the largest reached nearly 69 feet (21 meters) from snout to tail, according to National Geographic†
At 13 feet (4 meters) in length, the Tyndall ichthyosaurus is a medium-sized specimen dating from about 129 to 139 million years ago, in the early Cretaceous Period (about 145 million to 66 million years ago).
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The fossil came to Maxwell’s attention when it was first found in 2009 by paleontologist Judith Pardo-Pérez, who joined Maxwell’s research group in Stuttgart shortly after the fossil’s discovery. 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 named it “Fiona” after actress Cameron Diaz’s ogre character in the movie “Shrek” (Dreamworks, 2001), because the fossil’s preservative oxide layer made it green, much like its brave ogre namesake.
But it took 13 years for scientists to finally excavate and study Fiona’s remains, which Maxwell says isn’t unusual.
“There is often a long delay between the discovery of the fossil and the study of the fossil,” explains Maxwell. In this case, the delay was partly due to location: Tyndall Glacier is extremely remote, so every fossil from the site — including 23 other ichthyosaurs discovered alongside Fiona — had to be carefully removed by helicopter after excavations. Unfortunately, many more fossils were left behind. “We have nearly a hundred ichthyosaurs in the fossil deposit of Tyndall Glacier and many of them will unfortunately never be excavated, due to the difficulty of access, being in risk areas (cliff edge) and lack of funds,” Pardo-Pérez said. in a statement†
Specimens like Fiona, which were fossilized during pregnancy, are especially helpful to paleontologists because they offer a glimpse into multiple stages in that species’ life cycle. “For example, we can see how many embryos those species 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 give birth to live young rather than lay eggs as most modern reptiles do, she added.
Maxwell hopes the find will 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’s happening in half the world before the Mesozoic era [252 million to 66 million years ago]she said. “So these finds are very, very important to give a global perspective to our understanding of the Cretaceous oceans.”
Originally published on Live Science.
