Four new Rhamphorhynchus specimens added

Over the weekend
I added four new Rhamphorhynchus specimens to the large pterosaur tree (subset Fig. 1). Once again, each is distinct from one another and no two match in all traits…

Figure 1. Rhamphorhynchus cladogram with four new taxa.

Figure 1. Rhamphorhynchus cladogram with four new taxa.

…except
the one-third-size juvenile, commonly called “The Vienna specimen” NHMW 1998z0077/0001, which nests with the adult largest Rhamphorhynchus of all, BMNH 37002, n82 in the Wellnhofer 1975 catalog.

Fig. 5. Rhamphorhynchus specimens that have been bitten and fossilized with Aspidorhynchus, a Solnhofen fish of 60cm length.

Fig. 2. Rhamphorhynchus specimens that have been bitten and fossilized with Aspidorhynchus, a Solnhofen fish of 60cm length.

The four new specimens
include two specimens caught in the jaws of Late Jurassic fish (Fig. 2), the Imhof specimen and WDC CSG 255. Also included are BRI010, again from the Imhof collection and TMP 2008.41.0001, a sister to the dark wing specimen. The latter three bridge the gap between the n81 and n82 rare giants and the smaller more typical specimens, like the dark wing specimen, JME SOS 4784. The Imhof specimen nests basal to the giants.

Are all Rhamphorhynchus specimens congeneric? Or conspecific?
No. Many look similar, but on closer examination, or phylogenetic analysis, the differences are manifold, contra Bennett 1995.

  1. Some adults are tiny, others are mid-sized, and a few are relative giants
  2. Some have a short rostrum, but most do not.
  3. The finger and toe patterns vary greatly. The free finger sizes vary, too.
  4. Sternal complex shapes vary greatly.
  5. Some have a robust cervical series. Others do not.

Some things do not change between specimens

  1. The wing membrane has a shallow chord at the elbow, as in all pterosaurs.
  2. The nares and antorbital fenestra are both small
  3. The humerus is relatively short and the torso long such that when tucked posteriorly the elbow is still several vertebrae away from the anterior ilium.
  4. The teeth lean anteriorly
  5. The metatarsals spread and pedal digit 5 is relatively short.
Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 3. Prior to today’s additions, these were the taxa included in analysis. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O’Sullivan and Martill took the brave step of erecting a new species. Click to enlarge with new taxa added. 

Many of these things don’t become apparent
until you can see the whole lot reconstructed at one glance, or in phylogenetic analysis where you really do pay attention to details that lump and split clades and nodes.

References
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: Year-classes of a single large species. Journal of Paleontology 69:569-580.
Smith-Woodward A 1902. On two skulls of the Ornithosaurian Rhamphorhynchus. Annals and Magazine of Natural History, London, (7) 9:1-5.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33. Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149:1-30.

wiki/Rhamphorhynchus

Advertisements

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 )

Twitter picture

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

Facebook photo

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

Google+ photo

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

Connecting to %s