New Pterosaur Tree – Andres and Myers 2013

Pterosaur worker, Brian Andres, has produced a larger pterosaur tree than prior efforts by combining those prior efforts (Fig. 1). This was part of his 2010 PhD dissertation. The Wiki version (easier to read) can be seen here. I understand this tree will appear in a forthcoming (2014) volume entitled, “The Pterosauria.” Hope it avoids all past pitfalls, but judging by this tree (Fig. 1) and the description of the volume (“important new finds such as Darwinopterus“) we are due for another few years in the “dark ages.”

Sorry about that, kids. l’m really trying to fix things here by pointing out obvious errors.

According to Wikipedia
Andres’ phylogenetic analysis combines data mainly from three different matrixes: Kellner’s original analysis (2003) and its updates (Kellner (2004), Wang et al. (2005) and Wang et al. (2009)), Unwin’s original analysis (2003) and its updates (Unwin (2002), Unwin (2004), Lu et al. (2008) and Lu et al. (2009)) and previous analyses by Andres et al. (2005), Andres and Ji (2008) and Andres et al. (2010). Additional characters are taken from DallaVecchia (2009), Bennett’ analyses (1993-1994) and various older, non-phylogenetic, papers.

Figure 1. Click to enlarge. Pterosaur family tree produced by Andres 2010 and in press. Color added to show clades according to the large pterosaur tree that included several specimens of certain genera and included tiny pterosaurs, lacking here.

Figure 1. Click to enlarge. Pterosaur family tree produced by Andres 2010 and in press. Color added to show clades according to the large pterosaur tree (that included several specimens of certain genera and included tiny pterosaurs, lacking here). The indigo bar by Eosipterus indicates one specimen is indeed a ctenochasmatid, but the other is a germanodactylid, as we covered earlier. So, specimens are needed here, not just genera.

It’s big but still incomplete
Andres’ taxon list excludes distinct variations within certain genera, like Dorygnathus and Scaphognathus, that proved important in the large pterosaur tree. Andres’ taxon list also excludes all tiny pterosaurs. Those likewise proved important in the large pterosaur tree.

Strange bedfellows
The Andres’ tree nested several taxa that also nest together in the large pterosaur tree. However, the Andres tree also produces several nesting partners that don’t look alike. They don’t share many traits. For instance, Andres tree nests the basal anurognathid Dendrorhynchoides with the germanodactylids (Fig. 2) at the base of the “pterodactyloidea.” Few pterosaurs are so different from one another. It seems improbable that one would evolve from the other. In the large pterosaur tree this transition actually was several convergent transitions — and all sister taxa document a gradual accumulation of derived traits — not the skull-jarring leap shown here (Fig. 2).

Figure 3. According to Andres these two pterosaurs are sisters. This, obviously, is erroneous.

Figure 2. According to Andres these two pterosaurs are sisters. This, obviously, is erroneous.

Andres tree also nests the dorygnathid, Parapsicephalus (= Dorygnathus) purdoni with Dimorphodon (Fig. 3). Again, these two share very few traits. Click on the links above to see and read about pterosaurs that are more similar to these two, and you’ll see what I mean.

Figure 4. According to Andres, these two pterosaurs are close sister taxa. According to the large pterosaur tree, they nest far apart.

Figure 3. According to Andres, these two pterosaurs, Dorygnathus and Dimorphoson, are close sister taxa. According to the large pterosaur tree, they nest far apart.

There are several other misfits in the Andres tree, as shown by the various color codes (Fig. 1) that represent clades in the large pterosaur tree. For instance, Andres tree doesn’t recognize that azhdarchids and chaoyangopterids evolved from protoazhdarchids, like Beipiaopterus and Huanhepterus.

Some highlights
Andres tree does not put darwinopterids at the base of the “pterodactyloidea” but between Sordes and Changchengopterus and close to Scaphognathus. This is very close to results of the large pterosaur tree (Fig. 4).

Figure 1. Click to enlarge. Unwin and Lü note a resemblance between Darwinopterus and Germanodactylus. And that is certainly so, but only by convergence. Phylogenetic analysis indicates a closer relationship between the descendants of Scaphognathus and Germanodactylus. Arrows indicate phylogenetic order. Here the long neck evolved first with a smaller skull. Then the skull became longer in the lineage of Darwinopterus.

Figure 4. The evolutionary lines that gave rise to Germanodactylus and Darwinopterus according to the large online pterosaur tree by yours truly. Small changes, gradual accumulations of derived traits are shown here. No strange bedfellows.

Andres nests the Triassic Raeticodactylus and Preondactylus at the base of the Pterosauria. While MPUM6009 is ancestral to both, these nestings are not bad (Fig. 5).

The origin of the Pterosauria from basal Fenestrasauria

Figure 5. The origin of the Pterosauria from basal Fenestrasauria. This image is not current, but will update when enlarged. Note: Euparkeria is not involved here.

Some lowlights
Andres tree nests most ornithocheirids following the pteranodontids (Fig. 6). This means large teeth reappeared on a broad rostrum evolving from a toothless sword-like rostrum. Sharp rostrum germanodactylids make better ancestors for pteranodontids and scaphognathids make better ancestors for ornithocheirids via Yixianopterus (Fig. 6). The warp in the humerus deltopectoral crest is distinct in ornithocheirids and pteranodontids and evolved convergently.

Figure 6. Left - evolutionary lineage according to Andres in which toothless pteranodontids give rise to toothy ornithocheirids. On the right, corrected lineages for each.

Figure 6. Click to enlarge. Left – evolutionary lineage according to Andres in which toothless pteranodontids give rise to toothy ornithocheirids. Right –  corrected lineages for each clade.

At the base of the pterosaurs Andres uses the derived erythrosuchid, Euparkeria, which shares no traits with pterosaurs. He would have been better off using a tritosaur or fenestrasaur, but chose to ignore the literature on pterosaur origins (Peters 2000, 2002, 2007).

Andres nests anurognathids with darwinopterids in a false clade, “monofenestrata” in which the naris and antorbital fenestra are supposed to be confluent, evidently based on the bogus reconstruction of Anurognathus by Bennett 2007, which we dismantled earlier here and here.

Some thoughts
Since so many pterosaurs are preserved in a crushed fashion it is imperative that they be reconstructed in order to ascertain the identification of bony elements. Few other workers attempt this and Andres is not known for doing so.

It is also imperative that pterosaur workers know what a pterosaur is. Phylogenetic analysis (Peters 2000, 2007 and online studies) and character analysis (Peters 2013) demonstrate pterosaurs are not related to archosaurs, like Euparkeria, but to tritosaur fenestrasaurs.

Finally it is imperative that pterosaur workers employ the tiny pterosaurs in their analyses. The family tree will never make sense and will never produce gradual accumulations of derived characters unless the tiny pterosaurs are included.

References
Andres BB 2010. Systematics of the Pterosauria PhD dissertation. Yale University, 2010, 366 pages; 3440534
Andres B and Myers TS 2013. Lone Star Pterosaurs. Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 103: Issue 3-4, p 383-398.
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2013. A gradual accumulation of pterosaurian traits within a series of Lepidosauriformes. Rio Ptero Symposium 2013.

wiki/Phylogeny_of_pterosaurs 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.