The Family Tree of the Pterosauria 4 – Basal Eudimorphodontia

We’ve just looked at the base of the pterosauriabasal Dimorphodontia and derived Dimorphodontia (aka Anurognathidae). Now we shift our gaze to the base of ALL other pterosaurs – the Eudimorphodontia. This base includes the pointy-nosed pterosaurs shown in Figure 1 and begins with its namesake, Eudimorphodon. More details and references are found at reptileevolution.com.

Basal members of the Eudimorphodontia.

Figure 1. Click to enlarge. Basal members of the Eudimorphodontia.

Eudimorphodon ranzii
Eudimorphodon ranzii (Zambelli 1973, Wild 1978) was a large and robust Triassic pterosaur with multicusped teeth in the back of its jaws. When other Triassic pterosaurs were found that shared this trait this genus became a sort of wastebasket for many of them. Earlier workers did not realize that this was a trait retained from non-pterosaur fenestrasaurs such as Sharovipteryx and Longisquama. Distinct form MPUM 6009, Eudimorphodon was more than twice as large, with a longer snout and longer jaws. The skull and torso appear to be robust, with shorter hind limbs (unknown from the top of the shins down) and a larger sternal complex. The humerus was more robust, but the pelvis was reduced. The wing length is unknown. The femoral head was not set at right angles, so this clade retained sprawling femora.

Eudimorphodon cromptonellus
This tiny Eudimorphodon sister species (Jenkins et al. 1999), a third the size of the holotype (see above), is known from scattered bits and pieces. If it is an adult, it represents yet another size reduction between the major groups. This transition led to Campylognathoides, which does not have multicusped teeth and to Bsp 1994, which does. Here the foot and lower leg can be reconstructed with the foot slightly larger than the tibia and the tibia subequal to the femur, which is not typical of pterosaurs.

Campylognathoides
Several specimens are known of Campylognathoides and they differ significantly from one another, but in every one manual 4.1 reaches the elbow when the wing is folded. The most primitive of the Campylognathoides species is C. zitteli, the Paris specimen MNHN, Paris HLZ 50, or C4 in the Wild 1975 catalog).  It shares more traits with Eudimorphodon ranzii than any other Campy.

The  Cz specimen, SMNS 11879, Cz in the Wild (1975) was the giant of the clade with a larger head and a relatively shorter torso.

The C5 specimen SMNS 9787, C5 in the Wild (1975) catalog was similar but overall much smaller with distinct proportions.

Nesodactylus, a partial specimen from Cuba (Colbert 1969) AMNH FR 2000 , nests within this clade, so actually it should be called Campylognathoides hesperius. The sternum was not so wide, but it had a deep keel. The metatarsals were not bound together.

The C3 specimen or C. liasicus (Wellnhofer 1974) CM 11424, is the most derived Campylognathoides and the one sharing the most traits with Rhamphorhynchus.

Figure 2. Click to enlarge. The family tree of Rhamphorhynchus.

Rhamphorhynchus
Several recent reports nested Rhamphorhynchus with Dorygnathus, but that nesting was not recovered here. Bennett (1995) tested Rhamphorhynchus using statistics and decided that all known specimens were growth stages of one species. Bennett’s hypothesis was tested using cladistic analysis and found to be false. A lineage of increasingly derived Rhamphorhynchus was found, and besides, now we know from embryos that pterosaurs do not change shapes during maturity, something Bennett was not aware of at the time.

Rhamphorhynchus intermedius (St/Ei 8209, no. 28 in the Wellnhofer 1975 catalog) was half the size of the C3 specimen of Campylognathoides. In addition, it had a relatively shorter tail, shorter legs and shorter wings. R. intermedius represents the most primitive Rhamphorhynchus and the one closest to Campylognathoides.

An unnumbered and unpublished BMM specimen attributed to Rhamphorhynchus was half the size of R. intermedius, continuing the size reduction between genera. The jaws were shorter.

R. longicaudus B St 1959 I 400, no. 10 of Wellnhofer 1975 was a tiny specimen with a slightly longer snoutt.

R. longicaudus  BSP 1938 I 503a,  no. 11 of Wellnhofer 1975 had increasingly longer jaws without becoming very much larger overall.

Ironically, the largest Rhamphorhynuchus, R. longiceps (Smith-Woodward 1902) BMNH 37002, no. 81 in Wellnhofer 1975, follows the smallest specimens. I will have to dive back into some specimens to see if transitional specimens are known. Currently I know of none, but I have not looked at that many.

The medium-sized R. muensteri follows. The “darkwing” specimen nests here. Several other dozen specimens of R. muensteri would nest here if tested.

Several specimens of the larger R. gemmingi follow. No. 74, No. 43, No. 38 and No. 52 are in phylogenetic order, with No. 52 as the most derived and the last of this lineage. These taxa share m4.1 extending beyond the elbow and the naris is increasingly dorsal over the antorbital fenestra, among other traits. The oddball of the bunch is No. 75 with its extremely elongated snout and mandible.

Three Big-Eyed “Common Brown Sparrows”
Most basal Eudimorphodontia had a huge and pentagonal sternal complex, but these three did not. They were the basal members of the Sordesidae.

Bsp 1994 is known from scraps (Figure 1). A small triangular sternal complex sets it apart from Campylognathoides, etc. and well on the lineage to Dorygnathus.

Changchengopterus was much smaller (Figure 1) and known from a mandible and post-crania. These are the “common brown sparrows” of the pterosaur family tree. Not much to get excited about here, except the tail was much shorter and without the bony spars that stiffened it.

Sordes is the best known of this group, and the most misunderstood (Figure 1). Large curved teeth, big eyes, a relatively large skull and a torso about the same size mark Sordes as one to watch. From Sordes we get Dorygnathus which ultimately produces toothy ctenochasmatids and giant azhdarchids. We also get Pterorhynchus, Scaphognathus and all of the giant pterosaurs that descend from these.

Pterosaur family tree

Figure 3. The Eudimorphodontia within the pterosaur family tree.

Next time we look at the pterosaur family tree, Dorygnathus will be introduced, one of two TRUE transitional pterosaurs.

As always, I encourage readers to see the 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.

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.
Jenkins FA Jr, Shubin NH, Gatesy SM and Padian K 1999. A primitive pterosaur of Late Triassic age from Greenland. Journal of the Society of Vertebrate Paleontology 19(3): 56A.
Jenkins FA Jr, Shubin NH, Gatesy SM and Padian K 1999. A diminutive pterosaur (Pterosauria: Eudimorphodontidae) from the Greenlandic Triassic. Bulletin of the Museum of Comparative Zoology, Harvard University 155(9): 487-506.
Colbert EH 1969. A Jurassic Pterosaur from Cuba. American Museum Novitates, New York, 2370: 1-26.
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
Quenstedt FA 1858. Über Pterodactylus liasicus, Jahrbuch des Vereins vaterländischer Naturkundler in Württemberg, 14:299-336papers in palaeontology no. 80. The Palaenotological Association, London.
Smith-Woodward A 1902. On two skulls of the Ornithosaurian Rhamphorhynchus. Annals and Magazine of Natural History, London, (7) 9: 1-5.
Strand E 1928. Miscellanea nomenclatorica Zoologica et Palaeontologica, Archiv fur Naturgeschichte, 92: 30-75.
Wellnhofer P 1974. Campylognathoides liasicus (Quenstedt), an upper Liassic pterosaur from Holzmaden – the Pittsburgh specimen. Annals of the Carnegie Museum, Pittsburgh, 45: 5-34.
Wild R 1975. Ein Flugsaurier-Rest aus dem Lias Epsilon (Toarcium) von Erzingen (Schwäbisher Jura). -Stuttgarter Beiträge zur Naturkunde Serie B, Nr. 17: 1-16.
Wild R 1978. Die Flugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien. Bolletino della Societa Paleontologica Italiana 17(2): 176–256.
Zambelli R 1973. Eudimorphodon ranzii gen.nov., sp.nov. Uno Pterosauro Triassico. Rendiconti Instituto Lombardo Accademia, (rend. sc.) 107: 27-32.

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