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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
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 ...
The tooth whorls of Qianodus represent the oldest unequivocal remains of a toothed vertebrate, predating previously recorded occurrences [5] by about 14 million years. The specimens attributed to the genus come from limestone conglomerate beds of the Rongxi Formation exposed near the village of Leijiatun, Guizhou Province, China.
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).
A study of the arthrodire Compagopiscis published in 2012 concluded that placoderms (at least this particular genus) likely possessed true teeth contrary to some early studies. The teeth had well defined pulp cavities and were made of both bone and dentine. However, the tooth and jaw development were not as closely integrated as in modern ...
T. gregarium fossil (part and counterpart). Amateur collector Francis Tully [] found the first of these fossils in 1955 in a fossil bed known as the Mazon Creek formation.He took the strange creature to the Field Museum of Natural History, but paleontologists were stumped as to which phylum Tullimonstrum belonged in. [7] The species Tullimonstrum gregarium ("Tully's common monster"), as these ...
A Palmer oak in Jurupa Valley is estimated to be 13,000 to 18,000 years old. The plant, which looks like a sprawling, dark green shrub, is now at the center of a development battle.
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 ...