When did the earliest unequivocal Acanthodii fossils appear?
The earliest unequivocal Acanthodii fossils date from the beginning of the Silurian Period, some 50 million years before the first sharks appeared.
Questions about Acanthodii
Short answers, pulled from the story.
What is the scientific classification of Acanthodii?
Acanthodii is an extinct paraphyletic class of jawed fishes that possessed a skeleton made of cartilage but had fins reinforced with dentine spines.
How many distinct orders of Acanthodii existed?
Acanthodians have been divided into four distinct orders, including Climatiiformes, Diplacanthiformes, Ischnacanthiforms, and Acanthodiforms.
When did the Acanthodii lineage go extinct?
The Acanthodii died out in Permian times approximately 250 million years ago, with the youngest records found in Middle-Late Permian strata in the Paraná Basin of Brazil.
What is the relationship between Acanthodii and modern sharks?
Acanthodians were not true sharks but are considered a paraphyletic assemblage leading to cartilaginous fish, with some studies placing chondrichthyans nested among Acanthodii.
Where were the youngest Acanthodii fossils discovered?
The youngest records of the group are isolated scales and fin spines from Middle-Late Permian strata in the Paraná Basin of Brazil.