Looking at Rhamphorhynchus megadactylus

One of the larger, but not the largest, Rhamphorhynchus specimens is R. megadactylus (n52). It’s a classic roadkill fossil. Nearly all the parts are there, only difficult to segregate.

Figure 1. Rhamphorhynchus megadactylus in situ. Can you find the pelvis and prepubis here? How about both coracoids?

Figure 1. Rhamphorhynchus megadactylus in situ. Can you find the pelvis and prepubis here? How about both coracoids? The right femur is portrayed here in ghosted blue.

Some of the bones (skull, backbone, hind limb) are easy to identify. DGS (digital graphic segregation) helps a little in identifying the more difficult parts. As a reminder, a reconstruction and phylogenetic analysis are paramount to make sure you have identified all the parts correctly by fitting them together and that sister taxa share most traits.

Colorized bones in Rhamphorhynchus megadactylus.

Figure 2. Colorized bones in Rhamphorhynchus megadactylus.

Prior literature indicates that large specimens should have a fused scapulocoracoid. Here one remains fused after the taxonomic mixing, but the other does not.

Figure 3. Closeup of Rhamprhorhynchus megadactylus. Note the fused scapulocoracoid and the unfused one. Not sure yet what the bone below the upper humerus is. Perhaps the ventral portion of the humerus broken and shifted.

Figure 3. Closeup of Rhamprhorhynchus megadactylus. Note the fused scapulocoracoid and the unfused one. Not sure yet what the bone below the upper humerus is. Perhaps the ventral portion of the humerus broken and shifted.

Some other details are tiny and tricky. If you can, see if you can see the bones of manual digit 5 here (Fig. 4, one metacarpal and three phalanges, including the ungual).

Figure 4. Manual digit 5 is somewhere in this picture. Can you find it?

Figure 4. Manual digit 5 is somewhere in this picture. Can you find it?

Similarly, can you see the ungual (p5.3) at the tip of pedal digit 5 here (Fig. 5)?

Figure 5. Can you see the ungual of pedal digit 5 here in Rhamphorhynchus megadactylus, n52?

Figure 5. Can you see the ungual of pedal digit 5 here in Rhamphorhynchus megadactylus, n52? That’s metatarsal #4 sitting on top of digit 5.

References
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

1 thought on “Looking at Rhamphorhynchus megadactylus

  1. David Peters! Very interesting work, indeed! DGS…in some form or another…seems to me to be a very useful tool to add to a paleontologist’s research methodologies. Your knowledge of animal bones and your artistic expertise continue to amaze me. :o)

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