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Dinosaurs are defined under phylogenetic nomenclature as the group including the most recent common ancestor of Triceratops and modern birds, along with all its descendants. Birds are considered the only surviving dinosaurs, and contemporary paleontologists favor phylogenetic taxonomy over traditional classifications. Recent research has suggested a revision of dinosaurian systematics, proposing a new definition of Dinosauria to include sauropods and their relatives.

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59 views1 page

Under

Dinosaurs are defined under phylogenetic nomenclature as the group including the most recent common ancestor of Triceratops and modern birds, along with all its descendants. Birds are considered the only surviving dinosaurs, and contemporary paleontologists favor phylogenetic taxonomy over traditional classifications. Recent research has suggested a revision of dinosaurian systematics, proposing a new definition of Dinosauria to include sauropods and their relatives.

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Jezer Gonzales
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Under phylogenetic nomenclature, dinosaurs are usually defined as the group

consisting of the most recent common ancestor (MRCA) of Triceratops and modern
birds (Neornithes), and all its descendants.[7] It has also been suggested that Dinosauria
be defined with respect to the MRCA of Megalosaurus and Iguanodon, because these
were two of the three genera cited by Richard Owen when he recognized the
Dinosauria.[8] Both definitions cover the same known genera: Dinosauria
= Ornithischia + Saurischia. This includes major groups such
as ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated
herbivorous quadrupeds), ceratopsians (bipedal or quadrupedal herbivores with neck
frills), pachycephalosaurians (bipedal herbivores with thick skulls), ornithopods (bipedal
or quadrupedal herbivores including "duck-bills"), theropods (mostly bipedal carnivores
and birds), and sauropodomorphs (mostly large herbivorous quadrupeds with long
necks and tails).[9]

Birds are the sole surviving dinosaurs. In traditional taxonomy, birds were considered a
separate class that had evolved from dinosaurs, a distinct superorder. However, most
contemporary paleontologists reject the traditional style of classification based on
anatomical similarity, in favor of phylogenetic taxonomy based on deduced ancestry, in
which each group is defined as all descendants of a given founding genus.[10] Birds
belong to the dinosaur subgroup Maniraptora, which are coelurosaurs, which are
theropods, which are saurischians.[11]

Research by Matthew G. Baron, David B. Norman, and Paul M. Barrett in 2017


suggested a radical revision of dinosaurian systematics. Phylogenetic analysis by
Baron et al. recovered the Ornithischia as being closer to the Theropoda than the
Sauropodomorpha, as opposed to the traditional union of theropods with
sauropodomorphs. This would cause sauropods and kin to fall outside traditional
dinosaurs, so they re-defined Dinosauria as the last common ancestor of Triceratops
horridus, Passer domesticus and Diplodocus carnegii, and all of its descendants, to
ensure that sauropods and kin remain included as dinosaurs. They also resurrected the
cl

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