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Lampridiformes
The Lampridiformes are include about 50 living species of deep sea fishes, including the opahs, crestfish, ribbonfishes, and oarfish. These are acanthomorph teleosts which diverged at the end of the Cretaceous or in the succeeding Paleocene period, 60-70 million years ago.
Lampridiformes have a highly variable body form, but they are usually deep-bodied or elongate. The premaxilla completely excludes the maxilla from the gape. However, the jaws are highly protrusible, with a unique type of protrusible upper jaw. The maxilla, instead of being ligamentously attached to the ethmoid and palatine, slides in and out with the highly protractile premaxilla. The lambridiforms have 84-96 total vertebrae, but lack fin spines. The pelvic fins have 0-17 rays and are placed rather far toward the front of the animal. The dorsal fins are long, and tend to run most of the length of the body. They lack scales. The fishes are normally found at depth 100-1000m) but are pelagic, not bottom feeders.
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