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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]
The oldest remains attributed acanthodian-grade chondrichthyans are Fanjingshania and Qianodus from the Early Silurian of China, dating to around 439 million years ago. [ 7 ] [ 8 ] Compared to other contemporary groups of fish, acanthodians were relatively morphologically and ecologically conservative.
A possible gyracanthid known from a single worn fin spine, may be an indeterminate gnathostome or a junior synonym of Gyracanthus. [6] †Ankylacanthus [7] Valid. Emsian (Early Devonian). [7] Canada. [7] An acanthodian based on fin spines, possibly one of the oldest gyracanthids. †Antacanthus: Nomen dubium? Mississippian / Early Carboniferous ...
They are noted for their denticle whorls - oropharyngeal denticles that lined their branchial bars - which are thought to be homologous with other, later gnathostome teeth. In this sense, Loganellia may possess the earliest known dental structures related to modern teeth, and would have evolved in the throat, rather than through dermal ...
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).
The discovery of a newly identified species — the oldest saber-toothed animal found and an ancient cousin to mammals — fills a longstanding gap in the fossil record. ... serrated canine teeth ...
Chondrichthyes (/ k ɒ n ˈ d r ɪ k θ i iː z /; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.
If you thought teeth were only worth a couple bucks from the tooth fairy, think again. On a brand-new episode of "Antiques Roadshow" Monday, a Fred Myrick scrimshaw tooth got a price tag that ...