Revised November 4, 2020
with the news that two Skye pterosaurs have been presented in SVP abstracts, not the one I assumed. Neither has been published yet, so I don’t know if the accompanying illustrations represent one or the other.
This is the second time
the wonderful Skye, Scotland pterosaur has entered the SVP abstracts. The first was in 2019, covered here. Evidently, this specimen is still unnamed and unnumbered, so I wondered, what progress does the new set of authors bring to this specimen this year?
Figure 1. Skye pterosaur from traced from in situ specimens found online.
From the Jagielska et al. 2020 abstract:
“An incomplete fossil record limits understanding of pterosaurian macroevolution during the Middle Jurassic, a period associated with diversification of many major pterosaur clades.”
By contrast, the fossil record in the large pterosaur tree (LPT, 251 taxa) has no large gaps during the Middle Jurassic (Fig. 2) or otherwise. The fossil record is more complete than the authors realize, evidently due to taxon exclusion.
“The European Middle Jurassic pterosaurian record, until now, has consisted of numerous non-taxon specific specimens and included a single named genus, based on a partially preserved dentary.”
Are we forgetting all the many Dorygnathus specimens (Fig. 2)? Several are transitional to higher pterodactyloid-grade taxa, either directly (ctenochasmatids and azhdarchids) or indirectly through Scaphognathus (the rest of them; Peters 2007).
Figure 2. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.
Continuing from the Jagielska et al. 2020 abstract:
“Here we describe a new three-dimensionally preserved partial skeleton from the Bathonian Lealt Shale Formation of Skye, Scotland, that helps fill the Middle Jurassic pterosaur gap. It is the most complete fossil from the Jurassic sequence of the Scottish Hebrides, which commonly yields ichnofossils but only fragmentary archosaur remains, and the first nearly complete Middle Jurassic pterosaur from outside of China. The new pterosaur is mostly articulated and includes the skull (which retains delicate palatal, hyoid, and neurocranial elements), complete cervical and caudal vertebral series, fully preserved paired forelimbs with partially preserved wing phalanges, a disarticulated dorsal vertebral series and ribcage, and a poorly preserved sacral, pelvis and hindlimb region. It is the largest non-pterodactyloid on record, with an estimated 2 m wide wingspan.”
We also heard this in 2019. Since the authors have changed, perhaps no one told Jagielska et al. that this specimen was featured in an SVP abstract a year ago.
“The specimen represents a new genus and species diagnosed by several autapomorphies, including slender, curved humeral shaft; large teardrop-shaped lower temporal fenestra; a novel “jugo-lacrimal” fossa, and unique palatal arrangement with trident-shaped anterior vomer.”
As Larry Martin was quick to note, most autapomorphies can be found in other tetrapod taxa by convergence. So first, run the analysis. Then start describing some interesting traits.
“We conducted a phylogenetic analysis by combining several published datasets, which placed the new Scottish pterosaur within the paraphyletic array of non-monofenestratans commonly called the Rhamphorhynchinae, where it shares cranial similarities to the similarly-aged Chinese Angustinaripterus longicephalus.”
Sometimes more data nests taxa elsewhere, but their ‘several published datasets’ don’t include the LPT (subset Fig. 3). Borrowing other datasets usually absolves authors from mistakes made by prior authors, especially taxon exclusion issues. Colleagues, students: create your own datasets. Create your own reconstructions. By the way, in 2019 the earlier set of authors nested the Skye pterosaur with Darwinopterus and Wukongopterus, far from Angustinaripterus. The LRT nests the Skye pterosaur basal to the clade of wukongopterids (Fig. 3).
“We imaged the skull using microCT, which reveals a brain endocast with a large cerebellum and floccular region wrapped by thin, curved semi-circular canals of the inner ear, similar to closely related Rhamphorhynchus muensteri.”
The 2019 abstract likewise mentioned µCT scans. None of the above taxa are closely related to R. muensteri.
Figure 3. Subset of the LPT showing the nesting of the Skye pterosaur from available data (Fig. 1).
Continuing from the Jagielska et al. 2020 abstract:
“Along with the highly diverse but fragmentary Tayton Limestone Formation assemblage of England, the new specimen challenges the long-considered notion that the European Middle Jurassic was a time of low pterosaur diversity and anatomical disparity.”
One more specimen that we knew about last year will not challenge a ‘long considered notion’ that was never a notion to begin with. Hate to be snippy here, but hyperbole is not appropriate in science simply to elevate a notion or a cladogram, especially if it lacks dozens of pertinent taxa.
Jagielska N et al. (9 co-authors) 2020. An exceptionally well preserved pterosaur from the Middle Jurassic of Scotland. SVP abstracts 2020.
Martin-Silverstone E, Unwin DM and Barrett PM 2019. A new, three-dimensionally preserved monofenestratan pterosaur form the Middle Jurassic of Scotland and the complex evolutionary history of the scapulo-vertebrael articulation. SVP abstracts 2019. Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.