a break from a review of the SVP 2018 abstracts.
A new paper by Kundrát, et al. 2018
re-describes the Daiting specimen (Tischlinger 2009) attributed to Archaeopteryx and given a specific name A. albersdorfi (SNSB BSPG VN-2010/1; Kundrát et al. 2018, Late Jurassic, Lower Tithonian; Figs. 1, 2).
The skull of the Daiting specimen
is newly reconstructed here (Fig. 2). The former postorbital is now the squamosal. The former squamosal is here identified as three bones layers atop one another. The bones of the mandible are newly interpreted here.
Kundrát et al. provided several cladograms
based on data sets provided by Xu et al. 2011; Turner et al. 2012 and Godefroit et al. 2013. They “unanimously resolved [the Daiting specimen] as both a basal avialan and an archaeopterygid, but does not unequivocally discriminate between a paraphyletic or monophyletic Archaeopteryx.”
- Xu et al. 2011 cladogram: nests the Daiting specimen between Anchiornis + Xiaotingia and Archaeopteryx + Wellnhoferia, all derived from a Sapeornis–Yanornis clade.
- Xu et al. 2011cladogram (Xiaotingia deleted): nests the Daiting specimen between a Sapeornis–Yanornis clade and Archaeopteryx + Wellnhoferia,
- Turner et al. 2012 cladogram: nests the Daiting specimen basal to a different Sapeornis clade, all derived from Archaeopteryx.
- Turner et al. 2012 cladogram (3 taxa deleted): nests the Daiting specimen basal to a different Sapeornis clade, all derived from Archaeopteryx.
- Godefroit et al. 2013 cladogram: nests the Daiting specimen with Archaeopteryx, basal to the Balaur–Rahonavis clade, all derived from Xiaotingia.
Not all of the nodes in the above cladograms
include a gradual accumulation of traits in all derived taxa.
Kundrát et al. report:
“Archaeopteryx albersdoerferi is the only Bavarian archaeopterygid that exhibits co-ossification of the carpals and metacarpals, differing from modern flying birds in that the distal postaxial carpal (usually missing – perhaps cartilaginous – in other archaeopterygid specimens; (Wellnhofer 2009)) co-ossified with the metacarpal of the major digit rather than with the semilunate and postaxialmetacarpal.”
“The most noteworthy feature of Archaeopteryx albersdoerferi is that it accummulated several characteristics of maturity (discussed above) during the juvenile period of ontogeny that were not seen either in smaller or in larger specimens of Archaeopteryx lithographica.”
The coracoids of the Daiting specimen
are still rather disc-like in appearance, not strap-like as in Xiaotingia and birds. The Daiting specimen was not a flapping taxon, or not a good flapping taxon. That comes at the next node.
Earlier we looked at the variety of taxa present in Solnhofen birds,
(Fig. 3, 5) all of which have been called Archaeopteryx at their first publication. Later authors have renamed several of them. Remember, you can’t determine a genus or species without the context of a phylogenetic analysis.
Kundrát M, Nudds J, Kear BP, Lü J-C and Ahlberg P 2018. The first specimen of Archaeopteryx from the Upper Jurassic Mörnsheim Formation of Germany. Historical Biology 31(1):3-63.
Tischlinger H 2009. Der achte Archaeopteryx – das Daitinger Exemplar. Archaeopteryx. 27:1–20.
Wellnhofer P 2009. Archaeopteryx—the Icon of Evolution. München: Friedrich Pfeil.