| Ichthyodectiformes Temporal range: | |
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Division: | Teleostei |
| Order: | † Ichthyodectiformes Bardack & Sprinkle, 1969 |
| Subgroups | |
See text | |
Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus Ichthyodectes , established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest relatives of the teleost crown group. [1]
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They were most diverse throughout the Cretaceous period, though basal forms like Thrissops, Occithrissops and Allothrissops are known from the Middle-Late Jurassic of Europe and North America. They were almost entirely wiped out by the Cretaceous-Paleogene extinction event, but a single species, Saurocephalus lanciformis , appears to have survived into the earliest Paleocene (Danian). [2]
Most ichthyodectiforms ranged between 1 and 5 meters (3–15 ft) in length. Most of known taxa were predators, feeding on smaller fish; in several cases, larger ichthyodectiforms preyed on smaller members of the order. Some species had remarkably large teeth, though others, such as Gillicus arcuatus , had small ones and sucked in their prey. Heckelichthys preopercularis is a rare example of non-predatory ichthyodectiform, more likely to be microphagous, fed on small particles. [3] There is evidence that at least one species, Xiphactinus audax , may have been endothermic ("warm-blooded"). [4] Another genus, Dugaldia , may have been able to laterally open its mouth extremely wide in a manner akin to the modern sarcastic fringehead. [5]
