Lepidaspis
Encyclopedia
Lepidaspis serrata is an extinct heterostracan jawless fish
from Early Devonian
Canada
. Its genus name refers to the fact that the shield is composed of hundreds of tiny scales.
Although it is regarded as a heterostracan, its exact placement is regarded as incertae sedis
, as the fact that it is currently impossible to discern where its dorsal and ventral plates (which are made up of a mosaic of the aforementioned tiny scales) end or begin. Some experts regard it as being descended from the basal heterostracans of the Silurian
.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
from Early Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Its genus name refers to the fact that the shield is composed of hundreds of tiny scales.
Although it is regarded as a heterostracan, its exact placement is regarded as incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, as the fact that it is currently impossible to discern where its dorsal and ventral plates (which are made up of a mosaic of the aforementioned tiny scales) end or begin. Some experts regard it as being descended from the basal heterostracans of the Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
.
External links
- Pteraspidomorphi at Mikko's Phylogeny ArchiveMikko's Phylogeny ArchiveMikko's Phylogeny Archive is an amateur paleontology website maintained by Mikko Haaramo, a student at the University of Helsinki's Department of Geology, Division of Geology and Palaeontology....