Rare Hypsiprisca Fossil Fish | Green River Formation | Wyoming
Hypsiprisca sp.
Eocene (51.98 Million Years Ago)
Private Quarry, Green River Formation, Wyoming, USA
Preparation by Jim Tynsky
Fish approx. size: 1"
Matrix approx. size: 2.5" x 2.25"
Hypsiprisca remains one of the lesser-known fish from the Green River Formation. Its rarity and distinctive anatomy make it especially desirable to collectors and researchers alike.
Order Perciformes
Family Moronidae - C. liops, P. serrata, H. hypsacantha, and undescribed Priscacara & Hypsiprisca species.
Hypsiprisca is a rare genus of small ray-finned fish know from the Green River Formation. It reached a maximum known length of 3.5 inches. Most known specimens have been recovered from nearshore deposits within the Green River Formation, making well-preserved examples relatively scarce.
Compared to other moronids, Hypsiprisca has a more elongated body, a proportionally larger mouth, a less steep head profile, and a tail that is only slightly forked or nearly rounded. It also possesses a unique combination of anotomical features, including:
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Nine dorsal fin spines
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A continuous dorsal fin with no separation between the spiny and soft-rayed portions
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Long anterior-pointing spines along the lower margin of the preopercle
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Rounded margins on the second dorsal and anal fins
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A streamlined body adapted for active swimming