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The earliest recorded acanthodian, Fanjingshania renovata, [19] comes from the lower Silurian of China and it is also the oldest jawed vertebrate with known anatomical features. [19] Coeval to Fanjingshania is the tooth-based acanthodian species Qianodus duplicis [20] that represents the oldest unequivocal toothed vertebrate. Osteichthyes
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes).They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras.
The three forms of teeth, i.e., coniform cones, ramiform bars, and pectiniform platforms, probably performed different functions. For many years, conodonts were known only from enigmatic tooth-like microfossils (200 micrometers to 5 millimeters in length [ 17 ] ), which occur commonly, but not always, in isolation and were not associated with ...
The diagram is based on Michael Benton, 2005. [17] Dunkleosteus , among the first of the vertebrate apex predators , was a giant armoured placoderm predator . Amazichthys , a pelagic arthrodire from the Middle Famennian of the Late Devonian .
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
160,000 years ago, Homo sapiens idaltu in the Awash River Valley (near present-day Herto village, Ethiopia) practiced excarnation. [59] 130–80 ka Marine Isotope Stage 5 . Modern human presence in Southern Africa and West Africa. [60] Appearance of mitochondrial haplogroup (mt-haplogroup) L2. 80–50 ka MIS 4, beginning of the Upper Paleolithic.
The evolution of the mammalian middle ear appears to have occurred in two steps. A partial middle ear formed by the departure of postdentary bones from the dentary, and happened independently in the ancestors of monotremes and therians. The second step was the transition to a definite mammalian middle ear, and evolved independently at least ...
The mouth is located just behind the head, after a rostrum, on the underside of the body. It has a pair of cuticular jaws, supplied by strong muscles, and often bearing minute teeth. A "basal plate" on the lower surface that bears a comb-like structure is also present.