Raeticodactylus skull

Raeticodactylus (Fröbisch and Fröbisch 2006, Stecher 2008, Fig.1) is a skinny, nose–crested, Triassic pterosaur that nests with the holotype of Austriadactylus (Fig. 3), also a Triassic nose-crested pterosaur.

Figure 1. Raeticodactylus skull. Above, in situ and as originally interpreted. Middle: DGS tracing in color. Below: Reconstruction in lateral and palatal views. The missing part of the jugal may have lodged over quadrate, as it appears. The postorbital is broken into several pieces. The nasal extends a laminated layer over the premaxilla. The posterior pterygoid process is broken in situ and repaired here. One vomer is aligned with the premaxilla/maxilla suture. An ectopalatine (ectopterygoid + palatine) is displaced beneath the lacrimal. The mandible bones do not match the original drawing, but are closer to Eudimorphodon and other sister taxa. In all pterosaurs, the dentary approaches the coronoid process.

Figure 1. Raeticodactylus skull. Above, in situ and as originally interpreted. Middle: DGS tracing in color. Below: Reconstruction in lateral and palatal views. The missing part of the jugal may have lodged over quadrate, as it appears. The postorbital is broken into several pieces. The nasal extends a laminated layer over the premaxilla. The posterior pterygoid process is broken in situ and repaired here. One vomer is aligned with the premaxilla/maxilla suture. An ectopalatine (ectopterygoid + palatine) is displaced beneath the lacrimal. The mandible bones do not match the original drawing, but are closer to Eudimorphodon and other sister taxa. In all pterosaurs, the dentary approaches the coronoid process. Missing prefrontal and postfrontal indicated by black outline.

DGS and reinterpretation
The missing part of the jugal appears to have lodged over the quadrate. The coronoid, now on top of the jugal, has left a hole in the mandible posterior to the dentary. The postorbital is broken into several pieces and the central part is flipped (if correctly identified). The nasal extends a comb-like laminated layer over the premaxilla. The posterior pterygoid process is broken in situ and repaired here. One displaced vomer is aligned with the surface of the premaxilla/maxilla suture. An ectopalatine (ectopterygoid + palatine) is displaced beneath the lacrimal. The lacrimal is shorter than originally drawn. The mandible bones do not match the original drawing, but are closer to Eudimorphodon and other sister taxa. In all pterosaurs, the dentary approaches the coronoid process. The third anterior dentary tooth appears to have several roots, perhaps the result of tooth fusion. The prefrontal and postfrontal were not found.

All of these interpretations are tentative, but the reconstruction demonstrates these identifications fit established patterns. Take a look at the in situ postorbital. Only a colorized bone brings the pieces together visually. Dark outlines do not give such a visual cue.

Caviramus
An isolated mandible has been assigned to the genus Caviramus (Fig. 2). As in Raeticodactylus the articular extends posteriorly in an atypical fashion.

Figure 2. Caviramus (above) compared to Raeticodactylus (below) to the same length (on left) and to scale (on right). Caviramus mandible in lateral view showing the bony medial supports for the anterior teeth. The apparent mandible fenestra in Caviramus perhaps represents a missing coronoid.

Figure 2. Caviramus (above) compared to Raeticodactylus (below) to the same length (on left) and to scale (on right). Caviramus mandible in lateral view showing the bony medial supports for the anterior teeth. The apparent mandible fenestra in Caviramus perhaps represents a missing coronoid.

Nesbitt and Hone (2010) attempted to identify an antorbital fossa in Raeticodactylus, but this observation actually reflects the lateral thickness of the bone, reinforced to support the robust crushing teeth.

Figure 3. Austriadactylus (holotype) skull. Currently, with so few Triassic pterosaurs know, this is a sister to Raeticodactylus.

Figure 3. Austriadactylus (holotype) skull. Currently, with so few Triassic pterosaurs know, this is a sister to Raeticodactylus.

While we’re on the subject of Triassic pterosaur skulls,
let’s keep in mind Bergamodactylus (MPUM 6009, Fig. 4) and a sister to its predecessor, Longisquama, shown here to scale. Let’s remind ourselves that these fenestrasaur, tritosaur, lepidosaurs were very visual, especially when it came to secondary sexual characteristics. Crests, plumes and wings were all part of those differentiating packages once a pair of wings became standard equipment used for flying rather than solely for display.

http://www.reptileevolution.com/longisquama.htm

Figure 4. The skull of Bergamodactylus (MPUM 6009) together with that of Longisquama. Raeticodactylus had a more robust rostrum and mandibles, but was otherwise similar.

References
Fröbisch NB and Fröbisch J 2006. A new basal pterosaur genus from the upper Triassic of the Northern Calcareous Alps of Switzerland. Palaeontology 49 (5): 1081–1090. doi:10.1111/j.1475-4983.2006.00581.x. Retrieved 2007-03-02.
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233
Stecher R 2008. A new Triassic pterosaur from Switzerland (Central Austroalpine, Grisons), Raeticodactylus filisurensis gen. et sp. nov.. Swiss Journal of Geosciences 101: 185. doi:10.1007/s00015-008-1252-6. Online First

wiki/Raeticodactylus

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