Extinct genus of ray-finned fishes
Cheirolepis (from , 'hand' and 'scale') is an extinct genus of marine and freshwater ray-finned fish that lived in the Devonian period of Europe and North America. It is the only genus yet known within the family Cheirolepididae and the order Cheirolepidiformes. It was among the most basal 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 long. It had a streamlined body with small, triangular ganoid scales similar to those of the Acanthodii. These scales had a basic structure typical of many early osteichthyans, with a superficial of ganoine overlying dentine, and a basal plate of bone. "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 sharp teeth, could be opened very wide, allowing it to swallow prey two thirds of its own size.
Species.
The following species are known:
"C. schultzei" is known from Red 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 to "C. canadensis". Many species, including "C. aleshkai","C. bychovensis", "C. gracilis" &amp; "C. gaugeri" are only known from isolated scales. 
The species "C. sinualis" from Belarus is considered a "nomen nudum". The species "C. cummingae" , "C. macrocephalus" , &amp; "C. uragus" are considered conspecific with "C. trailli" 
References.
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