''Mayomyzon pieckoensis'' is an extinct
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
lamprey
Lampreys (sometimes inaccurately called lamprey eels) are a group of Agnatha, jawless fish comprising the order (biology), order Petromyzontiformes , sole order in the Class (biology), class Petromyzontida. The adult lamprey is characterize ...
that lived during the Late Carboniferous period, about 300 million years ago. It is the only known
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of the genus ''Mayomyzon'', which belongs to the family Mayomyzontidae. It is known from the
Mazon Creek fossil beds located in present-day
Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
.
Description
The fossil of ''M. pieckoensis'' is preserved as a carbon film in a concretion, which shows the outline of its body and some internal structures. The specimen is about 10 cm long and has a circular mouth with teeth, a single nostril, seven pairs of gill openings, and a dorsal fin that extends to the tail. The fossil also reveals that ''M. pieckoensis'' had pigmented eyes, which are rare among fossil vertebrates and suggest that it had some degree of vision.
[Janvier P. (1996). "Early vertebrates". Oxford University Press.]
''M. pieckoensis'' is considered to be one of the most basal lampreys, as it shares some features with the jawed vertebrates, such as the presence of a notochord and a cartilaginous skeleton. It also differs from modern lampreys in having fewer gill openings, larger eyes, and more teeth.
References
{{Taxonbar, from=Q20674968
Carboniferous fish of North America
†
Fossil taxa described in 1968