Trees of Life: Birds and Pterosaurs

Yale’s Richard Prum recently announced that the Tree of Life of Birds is almost complete. A genomic analysis of 198 species of birds was published in the Oct. 7 edition of the journal Nature. Prum reported, ““In the next five or 10 years, we will have finished the tree of life for birds.” I presume that means fossil taxa will also be included and scored by morphological traits because genes (genomic traits) are not available.

It is not the first time…
Trees of Life for Birds were announced earlier here, here, here and here.

Having been through a similar study, I support all such efforts. AND I will never attempt to add any but a few sample birds to the large reptile tree. Others have better access to specimens and they have a big head start on the process.

Unfortunately,
some workers have ignored the pterosaur tree of life. Recently Mark Witton ignored isometric growth patterns in pterosaurs to agree with Bennett (2013) that the genus Pterodactylus includes tiny short-snouted forms, mid-sized long-snouted forms (including the holotype, of course) and large small-heron-like forms. Witton reports, “Speaking of adulthood, it was also only recently that we’ve obtained a true sense of how large Pterodactylus may have grown. We typically imagine this animal as small bodied – maybe with a 50 cm wingspan – but a newly described skull and lower jaw makes the first unambiguous case for Pterodactylus reaching at least 1 m across the wings (Bennett 2013).”

We looked at Bennett’s paper earlier in a three part series that ended here. The taxon Witton refers to is actually just a wee bit larger than the holotype and is known from a skull, so wingspread can only be guessed. The tiny short-snouted forms are actually derived from the short-snouted scaphognathids as shown here.

The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Figure 1. Click to enlarge. The Pterodactylus lineage and mislabeled specimens formerly attributed to this “wastebasket” genus. Others have split the largest specimens of Pterodactylus from the others without employing a phylogenetic analysis.

You might recall
that one of the largest complete Pterodactylus specimens (Fig. 1) recovered by the large pterosaur tree was mistakenly removed from this genus and lumped with Ardeadactylus, a basal pre-azhdarchid, all without phylogenetic analysis.

Agreeing with Bennett,
Witton deletes some taxa that actually belong to this genus, while accepting others that do not belong, all based on eyeballing specimens without a phylogenetic analysis that includes a large gamut of specimens (that does not delete the tiny forms). Eyeballing taxa is not the way to handle lumping and splitting. Phylogenetic analysis is. We looked at the Pterodactylus wastebasket problem here.

References
Bennett  SC 2012 [2013]. New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift (advance online publication) doi: 10.1007/s12542-012-0159-8
http://link.springer.com/article/10.1007/s12542-012-0159-8

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