South Peace Historical Society

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  • Table of Contents

    • Part 1: First Nations of the Peace River Region
    • Part 2: The Fur Trade Era
    • Part 3: Transportation and Communication
    • Part 4: Old Timers and the Price of Land
    • Part 5: Dawson Creek: The Story of the Community
    • Part 6: Mysteries, Adventures and Indian Legends
    • Part 7: Arts, Crafts and Recreation
    • Part 8: Agriculture
    • Part 9: Church Histories
    • Part 10: Schools
    • Part 11: Health Care
    • Part 12: Industries and Enterprises
    • Part 13: Policing the Peace
    • Part 14: Pouce Coupe, Rolla, and Other South Peace Communities
    • Part 15: Chetwynd and the Fort St. John Area
    • Part 16: The Alberta Peace
    • Part 17: Natural History of the Peace River Region
    • Part 18: Interviews with Old Timers
    • Part 19: Remembering Our Veterans

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BN17-08: Ichthyosaurs – Some Technical Information

Recent Items – 1999

July 15, 1999

[Several examples of ichthyosaur fossils have been found in the Peace region. This article gives some technical information about these aquatic giants]

While dinosaurs ruled the land, the ichthyosaurs shared the seas of the world with the other great groups of large marine reptiles, the plesiosaurs and mosasaurs.

“Ichthyosaur” means “fish lizard.”

The earliest ichthyosaurs had long, flexible bodies and probably swam by undulating, like living eels. More advanced ichthyosaurs had compact, very fishlike bodies with crescent-shaped tails. The shape of these ichthyosaurs is like that of living tunas and mackerels, which are the fastest fish in the ocean; like them, the later ichthyosaurs were built for speed.

Rare fossils have been found that show ichthyosaurs actually giving birth to live, well-developed young; ichthyosaurs never had to leave the water to lay eggs. In fact, from their streamlined, fishlike bodies, it seems almost certain that ichthyosaurs could not leave the water. Yet they still breathed air and lacked gills, like modern whales.

Ichthyosaurs were not dinosaurs, but represent a separate group of marine vertebrates. Because ichthyosaurs were so specialized and modified for life in the ocean, we don’t really know which group of vertebrates were their closest relatives. They might have been an offshoot of the diapsids — the great vertebrate group that includes the dinosaurs and birds, the pterosaurs, the lizards and snakes, and many other vertebrates. On the other hand, some have suggested that the ichthyosaurs were descended from a distant relative of the turtles.

The first ichthyosaurs appeared in the Triassic. In the Jurassic, ichthyosaurs reached their highest diversity, and then began to decline. The last ichthyosaurs disappeared in the Cretaceous — several million years before the last dinosaurs died out. Whatever caused the extinction of the dinosaurs did not cause the ichthyosaurs to die out.

Ichthyosaurs diversified very quickly once they appeared. Several different body plans appeared in the Early and Middle Triassic. Shonisaurus popularis and probably Himalayasaurus tibetensis (both Late Triassic), reaching 15 metres, are the largest ichthyosaurs that have been described, but there are undescribed specimens that are larger. Among the smallest ichthyosaurs is Chaohusaurus geishanensis (Early Triassic), which probably did not reach 70 cm.

Source: The Museum of Paleontology, University of California, Berkeley, web site at www.ucmp.berkeley.edu/diapsids/ichthyosauria.html.

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BN17-09: Waterfowl Plan Comes to Peace »

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