Paul (1988) originally erected Avetheropoda as a taxon encompassing Ornitholestes, Compsognathus, Allosauridae, and Tyrannosauridae, as well as a few poorly known abelisaurids (e.g. Indosuchus). Avetheropoda, according to Paul (1988:189) included the “direct ancestors of birds.” The characters listed in Paul’s diagnosis included the furcula and semilunate carpal, which now apply to more basal theropods than he anticipated. Because Compsognathus, Coelurus and Archaeopteryx form a basal polytomy in the one phylogenetic tree in Paul (1988:fig. 10-1), however, it was not clear how to apply the name Avetheropoda to an alternative cladogram. Paul’s (2002:25) later asserted, to the contrary, that Avetheropoda had precedence over Neotetanurae. Yet his new tree (Paul 2002:fig.2.1) also shows a basal polytomy for Avetheropoda that includes “allosaurs,” Ornitholestes, and “compsognathians.”
Sereno (1994) coined the taxon Neotetanurae for a clade of advanced tetanurines that includes most of the taxa in Paul’s Avetheropoda. Approximately one month earlier (using publication dates), Holtz (1994) applied Paul’s taxon Avetheropoda to the same clade. No explicit definitions were proposed by either author at this time, but now two names were applied to the same clade (for a discussion of this, see Sereno 1999b). Neotatanurae was identified as a node-based taxon by Sereno (1997) and defined as such the following year (Sereno, 1998); the active definition of Neotetanurae used in this compilation is a first-order revision of that definition. Avetheropoda, by comparison, was first defined by Padian et al. (1999) using a node-based definition identical to that used for Neotetanurae by Sereno (1998). Holtz (2000) and Chure (2001) cited this same definition for Avetheropoda (note that Holtz’s paper of 2000 is sometimes cited as “1998” although published in 2000; the bibliography includes an accurate citation to Padian et al. 1999). But the genesis of the use of this definition for Avetheropoda requires further explanation.
This definition was inserted in a revision of the manuscript later published as Padian et al. (1999). This manuscript initially did not include a definition for Avetheropoda—until after the authors were sent a copy of a paper in press (Sereno 1998). Their revision included two relevant changes. First, they chose not to adapt or otherwise minimize the differences in phylogenetic definitions for theropods that existed between their manuscript and one in press (Sereno 1998). Instead, they added a section at the end of the paper (“Note Added In Revision”; Padian et al. 1999:77), referring to Sereno (1998) as a “paper in manuscript” rather than one that was in press and impossible to revise. Second, changes were also made in revision in the body of their paper, including the insertion of a node-based definition for Avetheropoda identical to that used for Neotetanurae (Sereno, 1998) and uncited use of Sereno’s (1998) term “node-stem triplet” (Padian et al. 1999:75).
Several subsequent statements in the literature regarding Neotetanurae and Avetheropoda, in this light, are misleading. Padian and Currie (1997:39) remarked that Avetheropoda . . .was formally defined in the phylogenetic system by Holtz (1994) . . . as the node within Tetanurae comprising the stem groups Coelurosauria and Carnosauria.” Holtz (1994), however, did not provide phylogenetic definitions for any of these taxa and used Carnosauria in quotes (a practice that ought to be continued). Padian and Currie (1997:39, 479) stated that Neotetanurae is a junior synonym of Avetheropoda, when clearly the former was defined prior to the latter. Holtz (2000) continued in this vein, stating that “indeed Sereno et al. (1997, 1998) used the same definition as above, rendering this term [Neotetanurae] a junior objective synonym of Avetheropoda.” That definition, for the record, was published first by Sereno (1998) for Neotetanurae and, while in press, borrowed for Avetheropoda.