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Earth’s First Known Giant

The skull of the first giant creature to ever inhabit the Earth, the ichthyosaur “Cymbospondylus youngorum” currently on display at the Natural History Museum of Los Angeles County (NHM). Image credit Natalja Kent, courtesy of the Natural History Museum of Los Angeles County (NHM)

Excavated from a rock unit called the Fossil Hill Member in the Augusta Mountains of Nevada, a well-preserved skull, along with part of a backbone, shoulder, and forefin, has been dated back to the Middle Triassic (247.2-237 million years ago).

The fossil is that of a newly discovered species of giant ichthyosaur.

Natural History Museum of Los Angeles County (NHM) Dinosaur Institute volunteer Viji Shook lying next to the skull of “Cymbospondylus youngorum” for scale, during the preparation of the specimen. Image credit: Martin Sander, courtesy of the Natural History Museum of Los Angeles County (NHM).

As big as a large sperm whale at more than 17 meters (55.78 feet) long, the newly named Cymbospondylus youngorum is the largest animal yet discovered from that time period, on land or in the sea. In fact, it was the first giant creature to ever inhabit the Earth that we know of.

A life recreation of “C. youngorum” stalking the Nevadan oceans of the Late Triassic 246 million years ago. Image credit: Illustration by Stephanie Abramowicz, courtesy of the Natural History Museum of Los Angeles County (NHM).

Dr. Martin Sander, paleontologist at the University of Bonn and Research Associate with the Dinosaur Institute at the Natural History Museum of Los Angeles County (NHM) explained:

“Ichthyosaurs derive from an as yet unknown group of land-living reptiles and were air-breathing themselves.

“From the first skeleton discoveries in southern England and Germany over 250 years ago, these ‘fish-saurians’ were among the first large fossil reptiles known to science, long before the dinosaurs, and they have captured the popular imagination ever since.

The importance of the find was not immediately apparent because only a few vertebrae were exposed on the side of the canyon. However, the anatomy of the vertebrae suggested that the front end of the animal might still be hidden in the rocks.

“Then, one cold September day in 2011, the crew needed a warm-up and tested this suggestion by excavation, finding the skull, forelimbs, and chest region.”

An ichthyosaur fossil surrounded by the shells of ammonites, the food source that possibly fueled their growth to huge. Image credit: Georg Oleschinski, courtesy of the University of Bonn, Germany.

In other mountain ranges of Nevada, paleontologists have been recovering fossils from the Fossil Hill Member’s limestone, shale, and siltstone since 1902. The mountains connect our present to ancient oceans and have produced many species of ammonites, shelled ancestors of modern cephalopods like cuttlefish and octopuses, as well as marine reptiles. All these animal specimens are collectively known as the Fossil Hill Fauna, representing many of C. youngorum’s prey and competitors.

Owing to their remote location, fossils have only recently been discovered in the Augusta Mountains. An international team of scientists led by Dr. Sander began collecting on public lands there 30 years ago, with fossil finds being accessioned to the Natural History Museum of Los Angeles County (NHM), since 2008. Image credit: Lars Schmitz

C. youngorum stalked the oceans some 246 million years ago, or only about three million years after the first ichthyosaurs got their fins wet, an amazingly short time to get this big. The elongated snout and conical teeth suggest that C. youngorum preyed on squid and fish, but its size meant that it could have hunted smaller and juvenile marine reptiles as well. 

C. youngorum will be permanently housed at the Natural History Museum of Los Angeles County, where it is currently on view. Visit NHM.ORG/ichthyosaur to learn more.

The researchers published their findings in Science.

A figure from the text comparing “C. youngorum” to a modern sperm whale as well as rates of body size evolution over time between ichthyosaurs and cetaceans. The lines trending towards the top indicate larger body sizes whereas those towards the bottom are smaller sizes. Time is displayed as starting from the point of origin of the group until their extinction (for ichthyosaurs) or present (for whales). Image credit: Illustration by Stephanie Abramowicz, courtesy of the Natural History Museum of Los Angeles County (NHM).

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