Description
About Cheirolepis trailli Early Ray-Finned Fish.
Physical Description
Cheirolepis is one of the larger fishes from the Orcandian basin. These fishes could reach over 30cm/a foot long in lenght. It was one of the predatory fishes as its jaws are lined with needle-like teeth. A C.trailli can be recognised by the rays in its fins and that these fins have a very sharp look to them (triangluar), an other feature is the large head and jaws.
Age and Distribution
Cheirolepis trailli is from the Middle Devonian of Scotland. This fish lived approximately 385 million years ago. At the time this area of Scotland was part of the Orcadian Basin, which was a huge complex of lakes that stretched for hundreds of miles. During this period plants started to rapidly colonize the land and fishes dominated nearly every niche of seas and lakes, hence why this period is also known as the “Age of Fishes”. co-inhabited the lake with other fishes like the acanthodians Mesacanthus, Cheiracanthus murchisoni and Diplacanthus crassismus, the osteolepids Gyroptychius, Osteolepis, and Thursius, the porolepid Glyptolepis, the lungfish Dipterus, the enigmatic Palaeospondylus gunni and the placoderms Dickosteus, Coccosteus, Pterichtyodes, Rhamphodopsis and Homostius.
About the Actinopterygii Cheirolepis trailli
Evolutionary Significance
Actinopterygians otherwise known as the ray-finned fishes, together with the Sarcopterygians (lobed-finned fishes) they form the Osteichthyes (bony vertebrates) which are the predominant group of fishes in the world. It is suggested that 99% of all fish belong to this group. In the Middle Devonian of Scotland Cheirolepis was the sole representative of Actinopterygians. The Actinopterygians suddenly appeared in the Devonian fossil records, it is believed that they would have an ancestor in the Silurian but that has not been found yet.
Taxonomy
Cheirolepis trailli belongs to the Cheirolepididae which is a subclass of the Actinopterygians (the ray-finned fish). There are no other known Cheirolepididae found in Scottish Middle Devonian. Although Scales have been found in the Baltic which could suggest that other Cheirolepididae lived in that region.
