Diplodocoidea

Diplodocoids Temporal range: Late Jurassic–Late Cretaceous, 154–93 Ma PreЄ Є O S D C P T J K Pg N
Holotype skeletons of Diplodocus carnegiei and Apatosaurus louisae, Carnegie Museum of Natural History
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	Saurischia
Suborder:	†Sauropodomorpha
Clade:	†Neosauropoda
Superfamily:	†Diplodocoidea Marsh, 1884 vide Upchurch, 1995
Type species
Diplodocus longus Marsh, 1878
Subgroups
Haplocanthosaurus Diplodocimorpha
Synonyms
Rebbachisauroidea Bonaparte, 1997

Diplodocoidea is a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias. 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 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.^[1] This taxon is also noteworthy because diplodocoid sauropods had the highest tooth replacement rates of any vertebrates, as exemplified by Nigersaurus, which had new teeth erupting every 30 days.^[2]

Taxonomy

The below taxonomy follows the study of Emanuel Tschopp, Octavio Mateus and Roger Benson, 2015:^[3]

• Diplodocoidea
  • Haplocanthosaurus
  • Diplodocimorpha
    • Rebbachisauridae
    • Flagellicaudata
      • Dicraeosauridae
      • Diplodocidae
        • Amphicoelias
        • Apatosaurinae
        • Diplodocinae

The phylogenetics of Diplodocoidea were reviewed in 2015 with a specimen-level phylogenetic analysis, as well as a species-level analysis. Their cladistic analysis is shown below.^[3]

Diplodocoidea

Haplocanthosaurus priscus Diplodocimorpha Rebbachisauridae Zapalasaurus bonapartei Limaysaurinae Cathartesaura anaerobica Limaysaurus tessonei Nigersaurinae Nigersaurus taqueti Demandasaurus darwini Flagellicaudata Dicraeosauridae Dyslocosaurus polyonychius Suuwassea emilieae Dystrophaeus viaemalae Brachytrachelopan mesai Amargasaurus cazaui Dicraeosaurus hansemanni Diplodocidae Amphicoelias altus Apatosaurinae ?Apatosaurinae gen. et sp. nov. Apatosaurus ajax Apatosaurus louisae Brontosaurus excelsus Brontosaurus yahnahpin Brontosaurus parvus Diplodocinae ?Diplodocinae gen. et sp. nov. Tornieria africana Supersaurus lourinhanensis Supersaurus vivianae Leinkupal laticauda Galeamopus hayi Diplodocus carnegiei Diplodocus hallorum Kaatedocus siberi Barosaurus lentus

References

1. http://www.ploscollections.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018304;jsessionid=B5ED8399160D7F46A7647ADE513F5B9C.ambra01
2. Sereno, PC; Wilson, JA; Witmer, LM; Whitlock, JA; Maga, A; et al. (2007). "Structural Extremes in a Cretaceous Dinosaur". PLoS ONE 2 (11): e1230. doi:10.1371/journal.pone.0001230. PMC 2077925. PMID 18030355.
3. Tschopp, E.; Mateus, O.; Benson, R.B.J. (2015). "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)". PeerJ 3: e857. doi:10.7717/peerj.857. PMC 4393826. PMID 25870766.