|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|E. Tschopp and O. Mateus 2013||Diplodocid sauropod with the following features not found in other sauropods:U-shaped notch separating the frontals anteriorly (Fig. 5); a rugose tuberosity that marks the anterodorsal corner of the lateral surface of the posterior cervical vertebrae (Fig. 10); posterior margin of the prezygapophyseal articular facet of posterior cervical vertebrae bordered posteriorly by a conspicuous transverse sulcus, separating the facet from the prezygapophyseal process (Fig. 10).
The following features are unique to Kaatedocus among Flagellicaudata or more inclusive clades: squamosals are restricted to the post-orbital region (unique for Diplodocoidea; Fig. 3); a straight anterior margin of the paired basal tuber in ventral view; anterior end of the prezygapophyses in mid- and posterior cervical vertebrae is formed by an accessory ventral process of the pre-epipophysis, that projects considerably anterior to the prezygapophyseal articular facet (Fig. 9).
The following features are unique to Kaatedocus among Diplodocidae: postparietal foramen present (Fig. 6); narrow, sharp and distinct sagittal nuchal crest on the supraoccipital (Figs 5, 6); and the narrowly diverging to subparallel posterior cervical neural spines (Fig. 10). Furthermore, the new taxon can be distinguished from adult Apatosaurus and Diplodocus by its closed or very reduced preantorbital fenestra (Fig. 4); the dorsal portion of lateral edge of the lacrimal that bears a dorsoventrally short laterally projecting spur (Fig. 6); the relatively rounded snout (Fig. 5); a second small fossa in the quadrate, medially at the base of the pterygoid ramus; and the ratio of length/maximum basal diameter of the basipterygoid processes being less than four. In contrast to Apatosaurus, Kaatedocus exhibits spinoprezygapophyseal lamina that are reduced to a ridge, or totally interrupted at the base of the prezygapophysis of anterior and mid-cervical vertebrae (Figs 7, 8). Kaatedocus is different from Diplodocus due to the presence of at least 12 maxillary and dentary teeth that are not restricted to the anteriormost part of the jaw (Fig. 3). It can be distinguished from Diplodocus, Tornieria and Barosaurus due to its relatively short mid-cervical centra (Elongation Index (EI) = centrum length/height of posterior cotyle < 4).