Wing types, Sharovipteryx, Longi

In his review on wing evolution Dietrich Schaller (1985) distinguished wing types according to function, type of wing attachment, and type of airfoil support.

Accordingly there are 'limb wings' and wings not involving limbs. The latter ones can be jointless, such as the pleural wings of Draco and kuehneosaurids, or single-jointed, such as the chitinous wings of insect flapping fliers.

What about the "enigmatic" Madygen beasts?

Sharovipteryx was an early limb-wing glider. Depending on the interpretation of wing topology it is reconstructed either with the fore- and hindlimbs connected by a wing membrane - representing the type of a 'skelobrachial glider' (sensu Schaller) - or with separate brachial (arm) wings and skelosal (leg) wings.

The latter case is discussed in particular by Dyke et al. (2006): Their modelling of the aerodynamic properties of different Sharovipteryx wing configurations demonstrates that a double delta wing morphology would have been the most advantageous for gliding (using certain input conditions based on model assumptions derived from the study of the morphology of the only fossil specimen).

Longisquama as a two-wing glider is not classified as easily. It would possess multi-segment and muli-jointed gliding wings which would constitute airfoils without further structures for support. Schaller did not consider such a configuration. Or else, it would have jointless wings comparable to the membranous muscle-supported flank wings of the gliding gecko Ptychozoon - but with the difference of being segmented, attached to the back and several times as long (minor drawbacks?).

References:

Schaller, D. (1985): Wing Evolution. In: Hecht, M.K., J.H. Ostrom, G. Viohl & P. Wellnhofer: The beginnings of birds. - Eichstätt (Freunde des Juramuseums), pp. 333- 348.

Dyke, G.J., R.L. Nudds & J.M.V. Rayner (2006): Flight of Sharovipteryx mirabilis: the world's first delta-winged glider. - Journal of Evolutionary Biology 19(4): 1040-1043.

World's Largest Mineral Collection

The opening week of Terra Mineralia is over, setting the signal for the new permament exhibition whithin the walls of the recently restored city castle of Freiberg, Saxony (the most beloved place of my studies besides Madygen).

The exhibition features spectacular pieces from the private collection which Erika Pohl donated to the TU Bergakademie Freiberg. Together with the quite large mineral stock of the Bergakademie's Mineralogical Institute the new gains make the Freibergian collection the largest in the world (...not bad for a town of 40-odd-thousand inhabitants).

The opening celebrations were also the chance for us geoscience students and scientists to communicate what we are doing to the general public and to people from other university departments - so we organized the

GeoDays 2008. Within the premises of Terra Mineralia we had a geo-photo competition, a poster exhibition, and a small program of lectures and presentations on 3D modelling, sand, soil, moon rocks, saxonian vertebrate fossils etc.

Among other GeoDays volunteers I was also involved in the children's program: For some hours between Thursday and Saturday I was responsible for the "raw material" station in a point-collecting game:

The children had to connect objects of daily use with the minerals which served as raw materials - an idea realized by Alexandra Käßner, another PhD student of the geological institute (nice one, Alex!)

.... though it is not easy to keep countenance when you have two kindergarten groups - ten kids each - standing around you, keen on solving the quest in order to get a point. (The price? - I think some small colourful polished piece of mineral).

Go here for some GeoTage impressions (including me in the first pic).

Rock-paper-scissors

Unpacking of the 2008 finds in a rather relaxed "subbotnik".
This year's fieldwork season turned out to be a good one for plants and for Philippe Moisan Tapia, palaeobotanist and graduate student at the University of Münster - he is doing his dissertation on the Madygen flora.

Triassic critters: Titanopterans

Among the most remarkable fossil insects from Madygen are the titanopterans which can reach wing spans of 50 cm. The Titanoptera form a subgroup of the Neoptera and were usually regarded as having an order rank when the Linnean taxonomic system is applied.

Recently, there was a revision done by Olivier Béthoux, who is currently working as a Humboldt research fellow at the geological institute of my alma mater (actually he is my "bureau mate"):

Béthoux (2007): Cladotypic taxonomy applied: Titanopterans are Orthopterans. - Arthropod Systematics & Phylogeny 65(2): 135- 156.

Recent orthopterans include grasshoppers and crickets. Olivier Béthoux shows on the basis of wing venation topology that members of a Permian "family" of Orthoptera - the Tcholmanvissiidae - are the closest relatives of the Triassic group Titanoptera. Such a relationship was also proposed by Madygen researcher A. G. Sharov as early as 1968 but later doubted by others.

The 'Titanopterida' are newly defined as a subgroup of the 'Tcholmantitanopterida' which are in turn a subgroup of Tcholmanvissiidae:

"Species that evolved from the (segments of) metapopulation lineage in which the character state ‘in forewing, CuPaα• + CuPaβ and CuPb having the same point of origin’, as exhibited by giganteus Tillyard, 1916 and vulgaris Sharov, 1968, has been acquired." (see page 145)

The cryptic formulas refer to higher order branches of the posterior Cubitus (CuP), a main wing veine.

Olivier's paper is interesting for another reason: As announced in the title he uses the relationship of titanopterans as an example for applying his concept of cladotypic taxonomy which on its own may be worth a post here (after I got the point). One part of his idea may be frightening for some biologists - as in the definition above there is no longer a need for binary nomenclature.

Fieldwork Photo of the Week

Blue-collar workers: undergrads Daniel & Juliane plus me.

Longisquama paper in press

Link to online first version:

Voigt, S. Buchwitz, M., Fischer, J., Krause, D. & Georgi, R.(2008): Feather-like development of Triassic diapsid skin appendages. - Naturwissenschaften

The paper introduces some new finds (appendage fragments found in 2007) and a specific interpretation which aspects of development can be inferred from the morphology of the complex appendage fossil.

Madygen: never heard? - for sure you did

hear about Longisquama and Sharovipteryx, the notorious "engimatic small diapsids" that are discussed every other year for their phylogenetic relevance and/or functional morphology.

Both come from a thin slice of lake sediments within the Triassic Madygen Formation, a several hundred meter thick succession of continental sedimentary rocks.

For the first time distinguished by KOCHNEV (1934) in an unpublished report and named after the village Madygen, the fossiliferous sediments came into the focus of Soviet palaeobiologists from Moscow, who carried out several excavations during the 1960s.

Madygen became a classic locality and primary source for Early Mesozoic insects. Moreover the group discovered macrofloral remains, molluscs, crustaceans, fish, an urodelan, a cynodont and two small skeletons of diapsid reptiles. The latter were described by the great Russian palaeoentomologist ALEXANDER G. SHAROV between 1966 and 1971.

Several approaches focussed on the sedimentology and stratigraphy of the Madygen Fm - a geological mapping and analysis of the flora by DOBRUSKINA (e.g. 1995) delivered a Ladinian- Carnian age.

During the last three years, palaeontological fieldwork in Madygen intensified again when the far-off realm of SW Kygrgyzstan was again headed for by a Moscovian group of palaeontologists and by a German research group.

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Some refs (see also linked WP articles of Longisquama & Sharovipteryx):

Sharov, A.G. (1966): [Unique discoveries of reptiles from Mesozoic beds of Central Asia.] - Bjulleten Moskovskogo Obscestva Ispytatelej Prirody, Otdel geologiceskij, 61 (2): 145- 146 (Moscow).

Dobruskina, I.A. (1995): Keuper (Triassic) Triassic Flora from Middle Asia (Madygen, Southern Fergana). - New Mexico Museum of Natural History and Science Bulletin 5: 1-49

Preamble

REMEMBERING the golden age of rising rationality when Haeckel convinced the unknowing masses with a multimedia show of colourful posters and bottles of (manipulated) embryos

WITH THE AIM of promoting the study of a worthwhile fossil site and its countless treasures

CRAVING for salvation in the heavenly realm of barrier-free communication

WITH THE CONFIDENCE that sharing our nerdy views can be therapeutical for us and alien beings alike

UNAWARE of the blogospherical disturbances and paracademic noise lying before us and

SALUTING to the free spirits of earth and life science

we, Michael of Freiberg, have started this palaeo/geo blog. "Hello world!"