Diplodocoidea is a superfamily of

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s, which included some of the longest animals of all time, including slender giants like '' Supersaurus'', ''

Diplodocus ''Diplodocus'' (, , or ) is an extinct genus of diplodocid sauropod dinosaurs known from the Late Jurassic of North America. The first fossils of ''Diplodocus'' were discovered in 1877 by S. W. Williston. The generic name, coined by Othnie ...

'', ''

Apatosaurus ''Apatosaurus'' (; meaning "deceptive lizard") is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, ''A. ajax'', in 1877, a ...

'', and ''

Amphicoelias ''Amphicoelias'' (, meaning "biconcave", from the Greek ἀμφί, ''amphi'': "on both sides", and κοῖλος, ''koilos'': "hollow, concave") is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during t ...

''. Most had very long necks and long, whip-like tails; however, one family (the dicraeosaurids) are the only known sauropods to have re-evolved a short neck, presumably an adaptation for feeding low to the ground. This adaptation was taken to the extreme in the highly specialized sauropod '' Brachytrachelopan''. A study of snout shape and

dental microwear Dental microwear analysis is a method to infer diet and behavior in extinct animals, especially in fossil specimens. It has been used on a variety of taxa, including hominids, victoriapithecids, amphicyonids, canids, ursids, hyaenids, hyaenodont ...

in diplodocoids showed that the square snouts, large proportion of pits, and fine subparallel scratches in ''Apatosaurus'', ''Diplodocus'', ''Nigersaurus'', and ''Rebbachisaurus'' suggest ground-height nonselective browsing; the narrow snouts of ''Dicraeosaurus'', ''Suuwassea'', and ''Tornieria'' and the coarse scratches and gouges on the teeth of ''Dicraeosaurus'' suggest mid-height selective browsing in those taxa.John A. Whitlock (6 April 2011
Inferences of Diplodocoid (Sauropoda: Dinosauria) Feeding Behavior from Snout Shape and Microwear Analyses
/ref> This taxon is also noteworthy because diplodocoid sauropods had the highest tooth replacement rates of any vertebrates, as exemplified by ''

Nigersaurus ''Nigersaurus'' () is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils o ...

'', which had new teeth erupting every 30 days. Most diplodocoids belong to Diplodocimorpha, a name first used by Calvo & Salgado (1995), who defined it as "''Rebbachisaurus tessonei'' sp. nov., Diplodocidae, and all descendants of their common ancestor." The group was not used often, and was synonymized with Diplodocoidea as the groups were often found to have the same content. In 2005,

Mike P. Taylor Michael Paul Taylor (born 12 March 1968) is a British computer programmer with a Ph.D. in palaeontology. To date, he has published 31 paleontological papers and is co-credited with naming three genera of dinosaur ('' Xenoposeidon'' in 2007 with ...

and

Darren Naish Darren William Naish (born 26 September 1975) is a British vertebrate palaeontologist, author and science communicator. As a researcher, he is best known for his work describing and reevaluating dinosaurs and other Mesozoic reptiles, including ...

reviewed diplodocoid phylogeny and taxonomy, and realized that Diplodocimorpha could not be synonymized with Diplodocoidea. Whereas the former was defined node-based, the latter was branch-based. '' Haplocanthosaurus'' and possibly ''

'' are non-diplodocimorph diplodocoids.

Taxonomy

The clade Flagellicaudata was erected by Harris and Dodson (2004) for the diplodocoid clade formed by Dicraeosauridae and Diplodocidae in their paper describing a new genus of sauropod dinosaur, ''

Suuwassea ''Suuwassea'' is a genus of Dicraeosauridae, dicraeosaurid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, Carbon County, Montana, United States. The fossil remains were ...

''. The authors carried out a phylogenetic analysis and noted that ''Suuwassea'', although more derived than Rebbachisauridae, is in a trichotomy with other families belonging to Diplodocoidea (Diplodocidae and Dicraeosauridae). Flagellicaudata was defined as a node-based clade consisting of the most recent common ancestor of '' Dicraeosaurus'' and ''

'' and all of its descendants. The word "Flagellicaudata" refers to long, whip-like tails of that animals (''flagellum'' is a Latin word meaning "whip" and ''cauda'' means in Latin "tail"). The phylogenetics of Diplodocoidea were reviewed in 2015 by Emanuel Tschopp, Octavio Mateus and Roger Benson with a specimen-level phylogenetic analysis, as well as a species-level analysis. Their cladistic analysis is shown below.

References

{{Authority control Dinosaur superfamilies