| Cheirolepis | |
|---|---|
 | |
| Life restoration of twoCheirolepis | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | †Cheirolepidiformes Kazantzeva-Selezneva, 1977[2] |
| Family: | †Cheirolepididae Pander, 1860[1] |
| Genus: | †Cheirolepis Agassiz, 1835 |
| Type species | |
| †Cheirolepis trailli Agassiz, 1835 | |
| Other species | |
See text | |
Cheirolepis (fromGreek:χείρkheír, 'hand' andGreek:λεπίςlepis 'scale')[3] is an extinct genus of marine and freshwaterray-finned fish that lived in theDevonian period of Europe and North America. It is the only genus yet known within the familyCheirolepididae and the orderCheirolepidiformes. It was among the mostbasal of the Devonian actinopterygians and is considered the first to possess the "standard" dermal cranial bones seen in later actinopterygians.
Cheirolepis was a predatory freshwater and estuarine animal about 55 centimetres (22 in) long. It had a streamlined body with small, triangularganoid scales similar to those of theAcanthodii. These scales had a basic structure typical of many earlyosteichthyans, with a superficial ofganoine overlyingdentine, and a basal plate ofbone.[4]Cheirolepis had well-developed fins which gave it speed and stability, and was probably an active predator. Based on the size of its eyes, it hunted by sight.Cheirolepis's jaws, lined with sharpteeth, could be opened very wide, allowing it to swallow prey two thirds of its own size.[5]
The following species are known:[6][7]
C. schultzei is known fromRed Hill, Nevada deposited during the Mid-Late Devonian boundary. The specimen from which this species was named, consisting of scales and a lower jaw, was originally referred toC. canadensis.[9] Many species, includingC. aleshkai,C. bychovensis,C. gracilis &C. gaugeri are only known from isolated scales.[8]
The speciesC. sinualis from Belarus is considered anomen nudum. The speciesC. cummingaeAgassiz, 1845,C. macrocephalusM'Coy 1848, &C. uragusAgassiz, 1835 are considered conspecific withC. trailli[10]
