The phylogenetic nestings of Campylognathoides and Rhamphorhynchus are today’s topics.
Dr. David Unwin nested Campylognathoides with Eudimorphodon. Rhamphorhynchus nested with Dorygnathus and together these two nested with Scaphognathus and Sordes.
Dr. Alexander Kellner also nested Campylognathoides with Eudimorphodon but nested Rhamphorhynchus alone at the base of all pterodactyloid-grade pterosaurs. Dorygnathus, Scaphognathus and Sordes all nested at more basal positions.
Andres et al. 1010
Dr. Brian Andres et al. nested Campylognathoides between Dimorphodon and Scaphognathus (and kin) + Sordes (and pterodactyloids + anurognathids). Rhamphorhynchus nested with Cacibupteryx between several dorygnathids including Dorygnathus and Angustinaripterus.
Figure 1. The Campylognathoidea.
The Present Tree
The present large tree, several times larger than any prior tree, and the first and only one to employ more than one specimen from several genera, nested the several species of Rhamphorhynchus following the several species of Campylognathoides and this clade was derived from Eudimorphodon cromptonellus and Eudimorphodon ranzii.
It is apparent that no one here agrees with each other, but some share certain elements. Importantly no prior trees nested Rhamphorhynchus with Campylognathoides. This is likely due to the choice of which specimen was used in analysis. The variety within each genus is substantial and certain Rhamphorhynchus specimens do indeed converge with certain Dorygnathus specimens. The large study promoted here used several specimens in order to alleviate this problem. However, what we’re most interested in today is the Campylognathoides to Rhamphorhynchus transition.
Figure 1. The size reduction at the Campylognathoides to Rhamphorhynchus transition. From left to right: CM 11424, the Pittsburgh specimen of Campylognathoides, St/Ei 8209 Rhamphorhynchus intermedius, and the BMM specimen of Rhamphorhynchus.
Our Transitional Players
The most derived Campylognathoides is the Pittsburgh specimen CM 11424, specimen C3 in the Wild (1975 catalog) from the Early Jurassic. The most basal Rhamphorhynchus is R. intermedius (Koh 1937) , St/Ei 8209, No. 28 in the Wellnhofer 1975 catalog from the Late Jurassic. Not surprisingly, the latter looks like a smaller version of the former and had plenty of time to evolve from it. We know of no Campys in the Late Jurassic and no Rhamphs in the Early Jurassic.
R. intermedius was considered a juvenile Rhamphorhychus by Bennett (1995), who used long bone measurements rather than a phylogenetic analysis. R. intermedius was larger than its phylogenetic successors, like R. longicaudus, but smaller than derived Rhamphorhynchus species, like R. longiceps. The phylogenetic size decrease between the specimens was due to serial precocious maturity and serial smaller egg size, as in several other pterosaur lineages.
Distinct from the C. liasicus, the skull of R. intermedius was relatively larger with a smaller naris and antorbital fenestra. Only one maxillary tooth was enlarged to fang status and like the premaxillary teeth, it was procumbent. The mandible was robust and convex dorsally. Several anterior dentary teeth also leaned anteriorly. The cervicals were slightly longer. The dorsal series was slightly shorter. The scapula and coracoid were not fused. This lack of fusion is not a sign of maturity, but follows phylogenetic lines. The deltopectoral crest was narrower. The ulna + radius was longer. The three distal wing phalanges were shorter and gracile. The prepubis perforation is expanded beyond the leading edge leaving an anterior process and a ventral process above and below the former perforation. The hind limbs were among the shortest among pterosaurs. The pedal digits were shorter than the metatarsals and digit V was longer than in Campylognathoides.
In pterosaurs phylogenetic size reduction appears to mimic juvenile characters. But we already know that pterosaur hatchlings were nearly identical to adults. That means the phylogenetic changes precede that hatchling stage and move back into the embryonic stage. Smaller pterosaur adults matured more rapidly than larger pterosaur adults. Smaller pterosaur eggs were ready to hatch sooner than larger pterosaur eggs. These changes produced the smaller wings, tail and legs seen in R. intermedius.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
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.
Koh TP 1937. Unterscuchungen über die Gattung Ramphorhynchus. – Neues Jahrbuch Mineralogie, Geologie und Palaeontologie, Beilage-Band 77: 455-506.
Padian K 2009. The Early Jurassic Pterosaur Dorygnathus banthenis (Theodori, 1830) and The Early Jurassic Pterosaur Campylognathoides Strand, 1928, Special Papers in Paleontology 80, Blackwell ISBN 9781405192248
Plieninger F 1907. Die Pterosaurier der Juraformation Schwabens. Paläontographica 53: 209-313 & pls 14–19.
Quenstedt FA 1858. Über Pterodactylus liasicus. Jahresheft des Vereins für Vaterlundische Naturkunde in Württemberg 14: 299-310.
Wellnhofer P 1974. Campylognathoides liasicus (Quenstedt), an upper Liassic pterosaur from Holzmaden – the Pittsburgh specimen. Annals of the Carnegie Museum, Pittsburgh, 45: 5-34.
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.