Martin-Silverstone, Unwin and Barrett 2019 bring us
news of a new Middle Jurrasic Scottish pterosaur: the Skye pterosaur.
From the abstract
“The Middle Jurassic was a critical time in pterosaur evolution – a series of major morphological innovations underpinned radiations by, successively, rhamphorhynchids, basal monofenestratans, and pterodactyloids. Frustratingly, however, this interval is also one of the most sparsely sampled parts of the pterosaur fossil record, consisting almost exclusively of isolated fragmentary remains.”
…other than all the many complete Jianchangnathus, Changchengopeterus, Pterorhynchus, Darwinopterus, and Dorygnathus specimens, that is. Why are these three pterosaur experts pretending these wonderfully preserved taxa don’t exist?
Figure 1. Skye pterosaur in ventral view traced from in situ specimen photos found online with limbs duplicated graphically. This preliminary data was enough to nest it in the LPT better than three PhDs with a set of µCT scans hampered by their much smaller unresolved pterosaur cladogram.
Martin-Silverstone et al. continue:
“Here we report on the most complete individual found to date, a three-dimensionally preserved, partial pterosaur skeleton recovered in 2006 from the Bathonian-aged Kilmaluag Formation, near Elgol, Isle of Skye, Scotland. Micro-CT scanning, segmentation, and 3D-reconstruction using Avizo has revealed multiple elements of the axial column, fore-, and hind limbs, many of which were fully embedded within the matrix and inaccessible via traditional preparation and imaging techniques.”
“Unique features of the coracoid distinguish the Skye pterosaur from all other species, indicating that it represents a new taxon.”
“The new specimen was included in phylogenetic analysis that was conducted using maximum parsimony in PAUP on a data matrix consisting of 61 taxa scored for 136 morphological characters. This analysis generated 544,320 MPTs.
OMG!!! What a confession!! That is a sign of a lousy cladogram!!
“The 50% majority rule tree places the Skye taxon as a basal monofenestratan in a clade with Darwinopterus, Wukongopterus, and, for the first time, Allkaruen, which was previously identified as non-monofenestratan.
The LPT confirms the nesting
of the Skye pterosaur with Darwinopterus
, but closer to Jianchangnathus
(Fig. 2). In the LPT, Alkaruen
nested basal to the ctenochasmatid, Pterodaustro.
Details on that here
Figure 2. Subset of the LPT showing the nesting of the Skye pterosaur from available data (Fig. 1). This is a terminal clade with no known descendants, contra Martin-Silverstone, Unwin and Barrett.
The Skye pterosaur, one of the earliest, most complete records for Monofenestrata, provides critical new insights into pterosaur evolution.”
The large pterosaur tree
(LPT, 241 taxa; subset Fig. 2) once again
finds no evidence for a monophyletic Monofenestrata and the entire LPT is resolved. If the Martin-Silverstone, Unwin and Barrett team added 180 taxa they would also find no evidence for a monophyletic Monofenestrata and their resolution would increase.
“The distal end of the Skye pterosaur’s scapula is expanded and articulated with the vertebral column, a feature shared with other basal mononfenestratans. Comparisons across Pterosauria show that this type of bracing was far more widespread than previously realized and seemingly present in many clades, with the exception of basal-most (Late Triassic) forms. The development of a notarium, providing additional stability and support, is confined to derived and often large and giant species and forms only part of the complex evolutionary history of the scapulo-vertebral contact.”
They could have simply said, a notarium is present. Instead they took a paragraph to do so, omitting many other traits that could have been mentioned. When scientific data is published, the authors of that data open their work for criticism and assistance. In that way errors are corrected and omissions are included.
Googling ‘Skye pterosaur’ results in several hits
including this classified ad from a year ago seeking a paleo student to work with a set of pterosaur expert PhDs. Hope it was a fulfilling experience for that student.
“Closing in January 2019: We seek a student with experience in studying and describing fossil and/or living animal specimens, comparative vertebrate anatomy, a broad background in biological and/or geological sciences, and experience or a willingness to learn statistical and CT techniques. As the student will be working with a large team, teamwork skills and a collaborative mindset are essential.” palass.org/careers
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. Journal of Vertebrate Paleontology abstracts.