Hyperoartia
Encyclopedia
Hyperoartia or Petromyzontida is a group of jawless fish that includes the modern lamprey
s and their fossil
relatives, the jawless fish of the class
Anaspida
. Examples of hyperoartians from early in their fossil record are Endeiolepis and Euphanerops, fishes with hypocercal tails that lived during the Late Devonian
Period. Some paleontologists
still classify these forms among the jawless armored fishes
.
The only hyperoartians surviving today are lampreys, classified in the Petromyzontiformes. The discovery of the fossil Priscomyzon, pushed back the oldest known occurrence of true lampreys to the Late Devonian
. The evidence of phylogeny, however, suggests that the lamprey lineage diverged much earlier from other vertebrates, rather than arising from ostracoderm
fishes. The origin of Hyperoartia may therefore extend back to the early Paleozoic
, if not earlier.
Lamprey
Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...
s and their fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
relatives, the jawless fish of the class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Anaspida
Anaspida
The Anaspida are stem gnathostomes, and are classically regarded as the ancestors of lampreys. Anaspids were small marine agnathans that lacked scales and paired fins, but have a striking highly hypocercal tail...
. Examples of hyperoartians from early in their fossil record are Endeiolepis and Euphanerops, fishes with hypocercal tails that lived during the Late 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...
Period. Some paleontologists
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
still classify these forms among the jawless armored fishes
Ostracoderm
Ostracoderms are any of several groups of extinct, primitive, jawless fishes that were covered in an armor of bony plates. They belong to the taxon Ostracodermi, and their fossils are found in the Ordovician and Devonian Period strata of North America and Europe...
.
The only hyperoartians surviving today are lampreys, classified in the Petromyzontiformes. The discovery of the fossil Priscomyzon, pushed back the oldest known occurrence of true lampreys to the Late 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...
. The evidence of phylogeny, however, suggests that the lamprey lineage diverged much earlier from other vertebrates, rather than arising from ostracoderm
Ostracoderm
Ostracoderms are any of several groups of extinct, primitive, jawless fishes that were covered in an armor of bony plates. They belong to the taxon Ostracodermi, and their fossils are found in the Ordovician and Devonian Period strata of North America and Europe...
fishes. The origin of Hyperoartia may therefore extend back to the early Paleozoic
Paleozoic
The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...
, if not earlier.