Elasmosauridae
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Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cret
Restoration showing two Elasmosaurus swimming with straight necks
Outdated restoration of Elasmosaurus showing its neck raised above water, by Samuel Wendell Williston, 1914
Gastroliths and bones (right) of an undetermined plesiosaur from Kansas
Placochelys BW
Elasmosaurus
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Elasmosaurus is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, at about 80.6 to 77 million years ago. The first specimen was discovered in
Elasmosauridae
…stage of the Late Cretaceous period (c. 130 to 66 mya). The taxon was initially erected in 1869 by Edward Drinker Cope to include the type genus Elasmosaurus with the related Cimoliasaurus, although he did not argue in detail why. Over the following years, many authors recognized this classification on the…
Officers at Fort Wallace, Kansas, in 1867. Theophilus H. Turner, who the same year discovered Elasmosaurus in the area, is second from left.
Back vertebrae of the holotype, 1869
Edward Drinker Cope's original 1869 reconstruction of Elasmosaurus, above, with the head on the wrong end and no hind-limbs, and holotype elements of E. platyurus (1–9) and E. orientalis (10), below
Cope's corrected 1870 reconstruction of Elasmosaurus, above