‘Pennaraptora’ — avoid this junior synonym

A new volume published by the AMNH
(eds. Pittman and Xu 2020), is all about the the putative clade, ‘Pennaraptora’ (Fig. 1). According to the preface, “Pennaraptora comprises birds themselves as well as the pennaceous feathered dromaeosaurids, troodontids, scansoriopterygids, and oviraptorosaurians.”

Here
in the large reptile tree (LRT, 1727+ taxa; subset Fig. 2) scansoriopterygids are birds, not oviraptorosaurian sisters. Oviraptorosaurians are terminal taxa in a larger clade that includes therizinosaurs and the CNJ79 specimen of Compsognathus and that clade is the sister clade of the Compsognathus holotype, struthiomimids and tyrannosaurids (Fig. 2). The last common ancestor of all these clades in the LRT is Aorun zhaoi (Choiniere et al. 2013; IVPP V15709, Late Jurassic 161mya).

So this multipart study on ‘Pennaraptorans’ is off to several bad starts. Neither ‘Aorun‘, nor ‘Tyrannoraptora’ (see below) are mentioned in the text. Several taxa have been omitted from this clade, including the last common ancestor.

Only two generic taxa and “their last common ancestor (LCA)”
should be enough to define a clade. Look what bad things can happen when you use four suprageneric taxa (Fig. 1). Don’t let in generic taxa that do not belong and omit generic taxa that do belong. Even so, and surprisingly, all taxa employed here are clade members. Unfortunately the clades and a few taxa are a little mixed up due to taxon exclusion.

Figure 1. Cladogram of the Pennaraptora from Pittman and Xu eds. 2020. Color overlays added to show clades in the LRT (Fig. 2).

Figure 1. Cladogram of the Pennaraptora from Pittman and Xu eds. 2020. Color overlays added to show clades in the LRT (Fig. 2).

Foth et al. defined Pennaraptora in 2014.
“Pennaraptora is a clade defined as the most recent common ancestor of Oviraptor philoceratops, Deinonychus antirrhopus, and Passer domesticus (the house sparrow), and all descendants thereof,”  Again, this definition only needs the first two taxa. Passer nests within “all descendants thereof”. Even so, this is a definition we can work with (Fig. 2).

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

In the LRT ‘Pennaraptora’
is almost a junior synonym of Compsognathidae (Cope 1871; Fig. 2) because two specimens of Compsognathus are basalmost taxa. However, Aorun is the last common ancestor taxon. It was originally considered the oldest known coelurosaurian theropod and a juvenile.

Figure 3. Aorun compared to several other theropods to scale.

Figure 3. Aorun compared to several other theropods to scale.

Figure 4. Aorun skull in situ and slightly restored. This is the basalmost tyrannoraptor.

Figure 4. Aorun skull in situ and slightly restored. This is the basalmost tyrannoraptor in the LRT.

According to Wikipedia, Aorun is now considered a member of
the Tyrannoraptora (Sereno 1999) defined as, “Tyrannosaurus, Passer their last common ancestor [Aorun] and all of its descendants.” So Pennaraptora (2014) is a junior synonym of Tyrannoraptora (1999). The two define the same clade in the LRT and share a last common ancestor.

Coelurosauria (von Huene 1914 is defined as theropods closer to birds than to carnosaurs. In the LRT Tyrannoraptora is also a junior synonym for Coelurosauria.


References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Choiniere JN, Clark JM, Forster CM, Norella MA, Eberth DA, Erickson GM, Chu H and Xu X 2013. A juvenile specimen of a new coelurosaur (Dinosauria: Theropoda) from the Middle–Late Jurassic Shishugou Formation of Xinjiang, People’s Republic of China. Journal of Systematic Palaeontology. online. doi:10.1080/14772019.2013.781067
Cope ED 1871. On the homologies of some of the cranial bones of the Reptilia, and on the systematic arrangement of the class. Proceedings of the American Association for the Advancement of Science 19:194-247
Foth C, Tischlinger H and Rauhut OWM 2014. New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers. Nature. 511 (7507): 79–82.
Huene F v 1914. Über de Zweistämmigkeit der Dinosaurier, mit Beiträgen zer Kenntnis einiger Schädel. Sep.-Abd. Neuen Jahrb. für Mineralogie Beil.-Bd.37:577–589. Pls. vii-xii.
Ostrom JH 1978. The osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Peyer K 2006. A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France, Journal of Vertebrate Paleontology, 26:4, 879-896.
Pittman M and Xu X eds. 2020.
Pennaraptoran theropod dinosaurs. Past progress and new Frontiers. Bulletin of the American Museum of Natural History 440; 353pp. 58 figures, 46 tables.
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.

wiki/Compsognathus
wiki/Tyrannoraptora
wiki/Aorun
wiki/Pennaraptora

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