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Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. Most gnathostomes have retained ancestral traits like true teeth , a stomach , [ 2 ] and paired appendages (pectoral and pelvic fins, arms, legs, wings, etc.). [ 3 ]
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 log structure was made at least 476,000 years ago, while the wood tools are slightly younger, under 400,000 years old. That places the materials in a time before our species, Homo sapiens ...
Researchers identified the creatures by their “degenerated” color and “extremely long” beak, according to a study.
The number of teeth and their function can vary widely between species, with some dolphins having over a hundred teeth in their jaws, while the narwhal has two functional teeth in its upper jaw which grow into long tusks in males. The tusk is used in feeding, navigation and mating and contains millions of sensory pathways, making it the most ...
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
Researchers have unearthed the oldest known wooden structure in Zambia, and it’s almost half a million years old, according to a new study. ‘Extraordinary’ structure has no real parallel in ...