Agadirichnus elegans pterosaur tracks rediscovered

Yesterday we looked at a recent online paper that expanded the list of pterosaur taxa present at the last days of pterosaurs and dinosaurs in the latest Cretaceous. Absent from that highly publicized work were the Maastrichtian pterosaur tracks made by ctenochasmatids (some quite large) listed below and the tupuxuarid skull described earlier.

Masrour et al. 2018
rediscover Maastrichtian (Late Cretaceous) dinosaurs, birds and enigmatic 8-9 cm pes tracks and 6cm manus tracks tentatively attributed to some sort of ‘Lacertilia’ under the name Agadirichnus elegans, first documented in Ambroggi and Lapparent 1954. The originals are now considered lost. The site in Morrocco was rediscovered. The enigma tracks were retrospectively identified as two pterosaur morphotypes.

Unknowingly,
these were the first pterosaur tracks ever named, preceding Pteraichnus by three years.

Etymology:
named after Agadir, the Moroccan city near the site.

Biggest takeaway:
There was a variety of pterosaurs in the Maastrichtian (Latest Cretaceous) that is presently underrepresented by skeletons (currently just giant azhdarchids and pteranodontids in rare fossiliferous strata worldwide).

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here one pedal track is matched to Middle Jurassic Darwinopterus, perhaps by convergence. But maybe not.

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here only one pedal track (B) is matched to Middle Jurassic Darwinopterus, perhaps by convergence. Note what appears to be pedal digit 5 beneath the heel.

The catalog of pterosaur pedes
(Peters 2011) was not cited, but I’ll use it to attempt a trackmaker identification.

A Pteranodon pes, UNSM 2062

Figure 1. A Pteranodon pes, UNSM 2062 as reconstructed plantigrade by Bennett (1991, 2001) and as reconstructed digitigrade. PILs added. Black elements are foreshortened during elevation into the digitigrade configuration. Some Pteranodon pedes were indeed plantigrade, depending on the species, but not this one based on PILs analysis. Note the distal and proximal tarsals are fused to each other.

Taxon B with pedal digit 3 the longest matches:

  1. Dimorphodon
  2. Darwinopterus (certain specimens only)
  3. Wukongopterus
  4. Ctenochasma elegans
  5. Pterodaustro
  6. Shenzhoupterus
  7. Pteranodon UNSM 2062 specimen only

Taxon B with digit 1 no longer than p2.2 matches

  1. Darwinopterus
  2. Wukongopterus
  3. Ctenochasma elegans
  4. Pterodaustro 
  5. Pteranodon UNSM 2062 specimen only

Taxon B with p4 subequal to mt 4 matches

  1. Pteranodon UNSM 2062 specimen only. Other tested Pteranodon specimens do not extend digit 3 beyond the others, as shown here. The only problem is: the fingers of Pteranodon cannot touch the substrate due to the long metacarpus relative to the short hind limbs. My guess: there was a large, as yet unknown, ctenochasmatid trackmaker in the Late Cretaceous. Ctenochasmatids had a short manual digit 1 and small dull claws on all digits matching the manus impression of Taxon A. Perhaps this was one of the giant ctenochasmatids, like Gegepterus, at present lacking data for both feet and fingers.

Taxon C with pedal digit 2 the longest, toes shorter than metatarsals and a narrow pes matches:

  1. Zhejiangopterus (probaby juvenile based on 6cm size)

Taxon D with pedal digit 2=3, toes shorter than metatarsals and metatarsal 4 much shorter than 1-3 matches:

  1. Ctenochasma

References
Ambroggi R and de Lapparent  AF 1954. Les empreintes de pas fossiles du Maestrichtien d’Agadir. Notes du Service Geologique du Maroc, 10:43–6.
Longrich NR, Martill DM, Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal. pbio.2001663
Masrour M, Ducla M d, Billon-Bruyat J-P and Mazin J-M 2018. Rediscovery of the Tagragra Tracksite (Maastrichtian, Agadir, Morocco): Agadirichnus elegans Ambroggi and Lapparent 1954 is Pterosaurian Ichnotaxon, Ichnos.  https://doi.org/10.1080/10420940.2017.1386661

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