''Tremataspis'' is a genus of an extinct osteostracan

agnatha Agnatha (; ) or jawless fish is a paraphyletic infraphylum of animals in the subphylum Vertebrata of the phylum Chordata, characterized by the lack of jaws. The group consists of both extant taxon, living (Cyclostomi, cyclostomes such as hagfish ...

n from the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

period of what is now

Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

''Tremataspis'' was about in length, and had an armored shield covering its head. Compared with its relatives, the shield was unusually elongated, covering the whole front of the body, and was more rounded in shape. It is thought that ''Tremataspis'' used its rounder shield to burrow in the ocean floor, searching for food. Because the shield consisted of one solid piece, it probably did not grow during the animal's life; presumably, the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e lacked the shield, which only appeared later in life. Tremataspis NT small

References

Osteostraci genera Fossils of Estonia Silurian fish of Europe {{Paleo-jawless-fish-stub