Thursday, December 31, 2015

Have a Stremmeia New Year!

To finish off the year, here's a taxon of ex-theropod not on anyone's dinosaur lists and which only gets 17 distinct Google results.  Perhaps you've heard of the 'Tendaguru Archaeopteryx', a supposed bird carpometacarpus from the Late Jurassic of Tanzania?  Well, as Molnar informed me over email, this was actually given a name by Nopcsa in 1930- Stremmeia scabra.  Its story follows...

Stremmeia Nopcsa, 1930
S. scabra Nopcsa, 1930
Tithonian, Late Jurassic
Upper Dinosaur Member of the Tendaguru Formation, Tanzania
- (HMN [edit- oh yeah, they changed the abbreviations] MB coll.) ?tibiale (24.5 mm) fused to ?fibulare (27.3)

Holotype of Stremmeia scabra (HMN coll.) in various views (after Stremme, 1919).

Comments- This specimen was discovered in 1910 associated with a Dicraeosaurus skeleton [edit- Stremme wrote the nonexistent combination 'Dicraeosaurus brancai' but specified skeleton S, so meant Brachiosaurus brancai] Giraffatitan's holotype, initially noted by Janensch (1914) as a bird carpometacarpus probably related to Archaeopteryx, then illustrated and described by Stremme (1919). The latter author could not determine what kind of reptile was represented, or if it was a metacarpus or metatarsus. Lambrecht (1933) noted that Stremme only mentioned Archaeopteryx in the context of differences between its metacarpus and the Tendaguru specimen, so dismissed Parkinson (1930) who stated Stremme considered them relatives. His own opinion was that the carpometacarpus resembled Rhea, so might indicate ratite relationships. Nopcsa (1930) meanwhile had identified the specimen as "carpals" of a pelobatid anuran, citing similarity to the tibiofibulare of Macropelobates (as noted by Stipanicic and Reig, 1957), and named it Stremmeia scabra. Among more recent authors, Hecht (1963) merely said that his reexamination of Stremmeia "showed that these bones are not frog remains" and Estes and Reig (1973) followed his interpretation. There has seemingly been no modern reevaluation of Stremmeia, or discussion of what its identity is if it is not a frog tibiofibulare.

Regardless of Hecht's comment, Stremmeia is more similar to e.g. Macropelobates' tibiofibulare than a maniraptoran carpometacarpus in the distinct proximal articular surfaces which form a flat outline instead of a single convex surface, and wide separation of the distal articular surfaces. This latter character is also unlike theropod metatarsals. However, the distal ends are more expanded transversely in anurans, and the distal articular surfaces seem to be simple instead of ginglymoid as in Stremmeia. Further differences from a coelurosaur manus include the large and quadrangular proximal surface of the shorter element (mcIII in most theropods) and sigmoid shape in side view. Whatever Stremmeia turns out to be, it is not theropod. Does anyone have another idea?

From left to right- carpometacarpi of Confuciusornis sanctus (Bonn specimen; after Goernemann, 1999) and Anchiornis huxleyi (holotype IVPP V14378; after Xu et al., 2008); metacarpals II and III of Archaeopteryx lithographica (Eichstatt specimen JM SoS 2257; after Wellnhofer, 1974); Stremmeia scabra (holotype HMN coll.; after Stremme, 1919); and tibiofibulare of Macropelobates osborni (holotype AMNH 6252; after Noble 1924).

References- Janensch, 1914. Ubersicht uber die Wirbeltierfauna der Tendaguru-Schichten. Archiv fur Biontologie. 3, 81-110.
Stremme, 1919. Uber die durch Bandverknocherung hervorgerufene proximale Verschmelzung zweier Mittelhand - oder Mittelfussknochen eines Reptils. Wissenschaftliche Ergebnisse der Tendaguru-Expedition. Archiv fur Biontologie. 4, 143-144.
Noble, 1924. A new spadefoot toad from the Oligocene of Mongolia with a summary of the evolution of the Pelobatidae. American Museum Novitates. 132, 15 pp.
Nopcsa, 1930. Notes on Stegocephalia and Amphibia. Proceedings of the Zoological Society of London. 1930, 979-995.
Parkinson, 1930. The dinosaur in East Africa: An account of the giant reptile beds of Tendaguru, Tanganyika territory. H.F. & G. Witherby. 192 pp.
Lambrecht, 1933. Handbuch der Palaeornithologie. Gebruder Borntraeger. 1024 pp.
Stipanicic and Reig, 1957. El "Complejo Porfírico de la Patagonia extraandina" y su fauna de anuros. Acta Geologica Lilloana. 1, 185-297.
Hecht, 1963. A reevaluation of the early history of the frogs. Part II. Systematic Zoology. 12(1), 20-35.
Estes and Reig, 1973. The early fossil record of frogs: A review of the evidence. In Vial (ed.). Evolutionary biology of the anurans: Contemporary research on major problems. University of Missouri Press. 11-63.
Wellnhofer, 1974. Das fünfte Skelettexemplar von Archaeopteryx. Palaeontographica. 147, 169-216.
Goernemann, 1999. Osteologie eines Exemplars von Confuciusornis aus der unteren Kreide von West-Liaoning, China. Archaeopteryx. 17, 41-54.
Xu, Zhao, Norell, Sullivan, Hone, Erickson, Wang, Han and Guo, 2008. A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin. Chinese Science Bulletin. 54(3), 430-435.