Samstag, 17. Oktober 2009

Madygen News 2009

Expedition. This year's two month expedition to Madygen, Kyrgyzstan, ends in about a week. Rather than merely assembling more fossils the task for 2009 was to carry out further observations concerning the facies architecture and fine stratigraphy of the Madygen Formation - in fact to solve the evolution of the Madygen depositional environment throughout the time comprised by the Triassic sequence of the Madygen SW outcrop area.

Since the ways of communication between Germany and the Kyrgyz outback are difficult I didn't get much of an opportunity yet to talk to Madygen project leader Sebastian Voigt (my de facto chief who is still in the field). But from what I've heard the paleoenvironment is now well explained and some furthergoing approaches, e.g. comparing the conditions of Madygen to those of the other (few) terrestrial lagerstätten of the Triassic, are now feasible.

Symposia contributions and papers

- on the flora:

Moisan, P., H. Kerp, S. Voigt, C. Pott & M. Buchwitz (2009): Cycadophyte foliage from the Triassic Madygen Formation, SW Kyrgyzstan Central Asia. Terra Nova 2009/3:81-82. [Abstract Volume of Annual Meeting of the German Paleontological Society in Bonn] ... the respective paper is soon to come.

- on kazacharthran body and trace fossils: ... still in the review process.

- on fish:

Kogan, I., K. Schönberger, J. Fischer, S. Voigt & M. Buchwitz (2009): A nearly complete Saurichthys specimen from the Triassic of Madygen (Kyrgyzstan, Central Asia). Terra Nova 2009/3: 63-64.

A first note on this find will published at the end of 2009 in Freiberger Forschungshefte.

SVP poster on egg capsules and teeth of hybodont sharks, which have been discovered in 2008: Fischer, J., S. Voigt, M. Buchwitz & J.W. Schneider (2009): The selachian fauna from the non-marine Middle to Late Triassic Madygen Formation (Kyrgyzstan, Middle Asia): preliminary results. JVP 29 (3, suppl.): 95A-96A.

- on chroniosuchians:

Buchwitz, M. & S. Voigt (2009): Locomotion aspects of a chroniosuchid carapace. In: D. Schwarz-Wings, O. Wings & F. Sattler (eds.): 7th Annual Meeting of the European Association of Vertebrate Paleontologis - Abstract Volume. Aachen, 2009, p.14.

Buchwitz, M. & S. Voigt (2009): Phylogenetic and functional implications of the chroniosuchian osteoderm morphology. Terra Nova 2009/3: 25.

I'm trying hard to finish these manuscripts just now. The first description of the new chroniosuchid species, focussing on the skull features, is 'in press'.

- about the thing that must not be named:

Buchwitz, M., S. Voigt & J. Fischer (2009): Dorsal appendages of You-know-what reconsidered: aspects of development and the link to the evolution of filamentous integumentary structures. JVP 29 (3, suppl.): 72A.

...there is another longer manuscript putting some effort into the detailed description/documentation and a discussion of some rather modest model (... but I cannot really tell yet whether an 'accept' is feasible in the near future).

- on the depositional environment of the Lagerstätte Madygen and its tetrapod localities:

Voigt, S., M. Buchwitz, J. Fischer, P. Moisan & I. Kogan (2009): Lagerstätte Madygen - outstanding window to a continental Triassic ecosystem. JVP 29 (3, suppl.): 196A.

Buchwitz, M., S. Voigt, J. Hentschke & P. Moisan (2009): The Triassic Madygen Formation (Kyrgyzstan, Middle Asia) features a new tetrapod locality. Terra Nova 2009/3: 25-26.

...the latter poster introduces some (real) archosaur finds from 2008.

Sonntag, 4. Oktober 2009

Questionnaire for Geobloggers
(incl. Paleobloggers)

The organisator is my former study colleage Lutz Geißler (now M.Sc. in geology), who is at the German forefront of publicising geoscience - with his web portals,, and with his postcard/ poster/ online campaign "Wir sind überall." ("We are everythere!" - referring to the role geoscience plays in daily life/ for the satisfaction of basic needs).

Mittwoch, 30. September 2009

SVP meeting reminiscences

My first SVP meeting was a bit of an eye opener for me:

Microtomography and 3D imaging, molecular paleobiology, advanced phylogenetical and biogeographical approaches, bone and tooth histology and microstructures, morphometrics, biomechanical modelling, any kind of studies on living functional/ ecological/ developmental analogues of fossil beings (actuopaleontology) - that's where the pot of gold is hidden.

... as a former geologist it gives me a certain urge to come to terms with what I should have learned about biology but only got briefly or autodidactically yet.

Apparently world is not as easy and small as it seems when you work as an isolated scholar for too long a time.

Montag, 28. September 2009

Reptile from the Petrified Forest of Chemnitz

In Early Permian volcaniclastic deposits of Chemnitz (Saxony, Germany) the partial skeleton of 30-cm-long basal reptile including a complete autopodium, further parts of the limbs, the vertebral column, thorax, and a fragmentary skull have been discovered last week by excavators from the Natural History Museum of Chemnitz.

This is the first tetrapod fossil from these deposits which are otherwise famous for their in situ silified tree stems ("Petrified Forest of Chemnitz").

Freitag, 11. September 2009

Symposia Summer: Are posters for kids? I daresay yes.

My former room mate (a post-doc and Humboldt scholar) once said that poster presentations rapidly lose their appeal once you have reached the age of speaking. And perhaps he was right after all.

Inlcuding this year's SVP meeting contributions I made 10 posters and was co-painterauthor of further 6 during the last three years (about two thirds about paleontology and one third on structural geology). That's enough to paper the walls of my of and my neighbour's lab room, but what did I get apart from that?

Flooding of the publication list? - Yes, but 20 abstracts = 1 peer-reviewed paper. To get something published cheeply should surely not be the point of postermaking - also considering the overall time you are investing for a mere halfpage of printed text.

Becoming a whiz in vector graphics? - Perhaps, but this is also part of normal publishing, lecture-preparation and thesis-writing, so you would have learned that anyway...

Feedback from experts? Negligible. Sometimes you are lucky and the right people are present and really interested in what you have done - but if they are not and yours is one of 50 posters displayed don't be too optimistic. Some people are so frustrated about the (probable) lack of response that they have their posters pinned up by an oral presenter from their own faculty and save the travel costs.

Dialogue with my former supervisor about a poster of mine:
- "Luckily I can give this to Maria. Symposia are such a waste of time!"
- "Obviously, you don't have yet understood what this part of science is about..."
- "Of course, I know about the importance of communicating your science and stuff... I was only teasing." (Afterwards pretending it was only irony, but meaning every word I said at first.)

I forgot something important: the winning of the poster prize! You can try. You need high-resolution colour fotos, high quality drawings, mirror finish paper, a sense for symmetry and for the golden section, and a vanilla ice topic (like dinosaurs, trilobites, Cambrian explosion, human origins).

And afterwards you can fancy yourself as the king of the symposium junior scientists layouters. Three cheers for the PP winner!

Why an oral presentation is better

Preparing an oral presentation is more time-consuming than making a poster: you have not only to put figures on a (rather patient) sheet of paper and do some write-around. Giving a talk you are really forced to make sense of your premisses, methods, data, results, conclusions and arrange everything in a sequence (only one dimension - time; a poster has two dimensions so you can illustrate complex interrelationships more easily and thus be more confuse without notice).

All these aspects help you directly with your scientific work: A well-structured presentation can easily make a well-structured publication and vice versa. And if there is a catch or lapse in reasoning you may become aware of it in the course of trying to explain your model to others.

With an oral presentation you get a real audience: Even if no one is interested in your topic common politeness makes them stay still and gives you the power to waste 15 minutes of the life time of 50 or 100 or 200 listeners. What a feeling of might!

If you are provocative you can even stir up a reaction. Compare posters and talks to potted plants and dogs. A dog/presenter is barking at you if he wants attention and thus you feel pushed to show him his place, the poster/ potted plant is simply hanging/ standing around and withers...

So give a talk if you have the guts!

Mittwoch, 12. August 2009

Fieldwork photo of the week

Some parts of the Madygen succession are particularly rich in plant remains inluding calamite stems accumulated in thin, sometimes coaly siltstone layers.

Samstag, 1. August 2009

Contributing to Wikipedia as a paleontologist/ geoscientist

There was a time when Wikipedia articles on palaeobiological and geoscientific topics where almost exclusively abysmal, including unreferrenced children's-book-like fossil animal portrayals 30 years behind the state-of-the-art.

That there has been a change during the last years, is more or less the consequence of the infusion of expert or semi-expert knowledge. Compare this and this version of the English Wikipedia article on a famous fossil taxon and you may acknowledge that a 5 year riping process can result in a nice and relatively up-to-date encyclopedia article.

Scepticism from the scientific community had different causes:

(1) unreliability as a data source/ lack of references - these problems were mostly solved when the community of WP writers established higher standards and agreed on that all major points made by an article have to be supported by independent sources.

(2) WP-related plagiarism by students. I suppose this is merely a problem of teaching youngsters the difference between right/honest and wrong/inhonest use of source texts and nothing Wikipedia can be blamed for.

(3) potential influence by people with a special agenda. Mostly neutralized by the overload of sensible/ unbiased Wikipedia workers. In most cases the WP community has enough background knowledge - so that unsupported/biased statements are recognized and rejected/presented in a neutral way.

There is also the question of utility, especially from the expert's point of view...

Why writing WP articles can be a worthwhile operation...

(1) Your contribution will be read. Search engines mostly place Wikipedia articles very high on the list. Anyone searching your article's lemma will find your text and use it. Thus you will be the provider of primary insight into a specific scientific topic.

Your article may be helpful even for serious research - namely for scientists of related fields searching for the explanation of a term (and references to further technical literature/ online sources).

(2) You can bring rarely publicised aspects of your science to public awareness by the choice of the topics you are writing about. By creating a featured article on a rare species of ammonoids you can direct the focus of paleo-enthusiasts to an otherwise neglected field (you gain more publicity for what is really at the heart of your interest).

(3) Sometimes it is a good excercise to recount for a non-specialist audience what appeared plausible in the internal discourse among scientists of your field. You may find that some concepts are hard to explain (and perhaps don't make much sense when in the cold light of day...).

This list could be could be continued.

Hindrances for new expert authors?

Frequent misunderstandings about the Wikipedia project are listed under "What Wikipedia is not" - you should read this to prevent later disappointments.

There are some Wiki formats - mostly as easy or easier to handle than HTML codes - and you are facing a growing body of rules and conventions. A recipe is to copy and paste the style/format features of an existing article code and to fill in your new content.

Don't argue too much about styles and formats with established Wikipedia users. Your primary aim as a specialist should be to provide up-to-date information, scientific background and overview knowledge, and corrections on misconceptions/ misunderstandings which often arise from the popularization of science.

If you out yourself as an expert you will find that amateurs among the experienced Wikipedia users will give you much support at the beginning and back you up in discussions (which can arise if you are working on controversial topics).

My own Wikipedia experience

I had my first edits in the German Wikipedia in 2005 when I was still an undergrad. If English is not your mother tongue you may think about editing articles in your own language WP, but mostly in the en:WP there is more substance to start with.

In any case you will find that much work is to be done and that you have to be selective with your engagement. Look at the points that you believe are most important and easily done. If you have done a literature search for your professional work you may use some of the data again for a WP article. If you are a PhD student, be aware of the Wikipedia procrastination potential!

Samstag, 25. Juli 2009

EAVP Meeting 2009 in Berlin, Germany

This week the European Associatuon of Vertebrate Paleontologists had its 7th annual meeting at the Humboldt University of Berlin Museum of Natural History, organized by Daniela Schwarz-Wings and her team.

Between Tuesday and Thursday about 34 oral presentations were held and 22 posters were displayed. Sorted systematically:

reptiles: 19.5 oral presentations (dinosaurs: 11) + 10.5 (7) posters
synapsids: 8.5 (mammals: 7) + 6.5 (6)
fish/ sharks: 3 + 3.5
anamniote tetrapods: 3 + 1.5

Apparently the EAVP is mostly a paleoherpetological society.

The two field trips organized for Friday covered the Rüdersdorf Muschelkalk Quarry (which yielded Nothosaurus, Placodus and others critters of the marine Middle Triassic) and the Pleistocene Rixdorf horizon of Niederlehme to the SW of Berlin.

Christian A. Meyer from Basel became new president of the EAVP, he takes the office over from Eric Buffetaut who is new editor-in-chief of the society's online-only journal Oryctos. Next year the meeting will be held in Aix-en-Provence in southern France, Greece is planned for 2011.

Sonntag, 28. Juni 2009

Chroniosuchians and stay in Moscow

To resolve the riddle: The bonified eyeball from the last post represents a a ball-shaped intercentrum of a chroniosuchid from the Permian of Russia.

In chroniosuchian reptiliomorphs the intercentra (white arrows) are interlocked with the amphicoelous pleurocentra in a ball-and-socket-like fashion. The image on the left shows some section of a Chroniosuchus vertebral column in ventral view. Intercentra become bony balls only in the adult individuals - not fully bonified in sub-adults and juveniles they are preserved with a crescent, disk-like or ellipsoidal shape.

Also, the fusion of the neural arch with the pleurocentrum - a feature otherwise characteristic for "higher reptiliomorphs" such as seymouriamorphs and diadectomorphs - is only completed in the course of ontogenesis (so that you can find suture lines in the subadult individuals).

Moscow: Paleontological Institute and Museum of the Russian Academy of Sciences (PIN)

The paleo-style PIN building has a castle-like rectangular shape with an inner courtyard featuring life-size sculptures of fossil critters from Russia and areas of the former Soviet Union. The exhibition has almost everything you wish for as a vertebrate enthusiast (here depicted: the two-story dinosaur hall). Rich in type specimens the collection is essential for some and important for many studies - so earlier or later many of the fossil vertebrate people spend some time there.

Concering the Chroniosuchia: With the exception of bystrowianid chroniosuchian remains from Kupferzell, Germany (Witzmann et al. 2008) and China (Young 1979) and some rather questionable Chinese chroniosuchid chroniosuchians (Li & Cheng 1999), all yet described Permian and Triassic chroniosuchian taxa come from the European part of Russia and are mostly archived in the PIN. I am thankful to Valery Golubev who helped me a lot during my week of stay when I was studying the type materials and to Jury Gubin who nicely put up with me in his room.

Some literature on chroniosuchians

Here considered: titles also available in English (plus the Chinese ones mentioned above).

Golubev, V. K. (1998).
"Narrow-armored Chroniosuchians (Amphibia, Anthracosauromorpha) from the Late Permian of Eastern Europe." Paleontologicheskij Zhurnal 1998(3): 64- 73. [Russian, English]

Golubev, V. K. (1998). "Revision of the Late Permian chroniosuchians (Amphibia, Anthracosauromorpha) from Eastern Europe." Paleontologicheskij Zhurnal 1998(4): 68- 77. [Russian, English]

Golubev, V. K. (1999).
"A new narrow-armored chroniosuchian (Amphibia, Anthracosauromorpha) from the Late Permian of the East Europe." Paleontologicheskij Zhurnal 1999(2): 43- 50. [Russian, English]

Li, J., Cheng Z. (1999). " New anthracosaur and temnospondyl amphibians from Gansu, China." Vertebrata PalAsiatica 37(3): 234- 247. [Chinese with English abstract]

Novikov, I. V., M.A. Shishkin (2000). "Triassic chroniosuchians (Amphibia, Anthracosauromorpha) and the evolution of the trunk dermal ossifications in the bystrowianids." Paleontological Journal 34(supplement): S165- S178. [English]

Novikov, I. V., M.A. Shishkin, V.K. Golubev (2000). Permian and Triassic anthracosaurs from Eastern Europe. The Age of Dinosaurs in Russia and Mongolia. M. A. S. M.J. Benton, D.M. Unwin, E.N. Kurochkin. Cambridge, Cambridge University Press: 60- 70. [English]

Witzmann, F., R.R. Schoch, M.W. Maisch (2008). "A relic basal tetrapod from the Middle Triassic of Germany." Naturwissenschaften 95(1): 67- 72. [English]

Young, C. C. (1979). "A new Late Permian fauna from Jiyuan, Honan." Vertebrata Palasiatica 17: 99- 113. [Chinese with English abstract]

Mittwoch, 24. Juni 2009

Bonified eyeball

Or what the hell is this?

Dienstag, 26. Mai 2009

Lineage concept vs cladistics
in continental biostratigraphy

The white hair of my chief Ph.D. supervisor is to some degree explained by his livelong efforts to get a grip on Carboniferous to Permian continental biostratigraphy - trying out different groups such as cockcroaches, conchostracans, freshwater sharks, and amphibians.

One of the underlying concepts which I suppose I will always find hard to believe is the idea of searching for and finding so-called lineages, i.e. series of species occurring subsequently in the stratigraphic record which show stepwisely distinct anatomies because each species has descended from the respective next-oldest species.

Of course every species has an ancestor and many have descendants but how can I define them from the fossil record? Is there not the typical problem of epistemic vagueness of the ancestor in any kind of phylogeny (e.g. discussed by Wolf-Ernst Reif in some of his many theoretical papers on cladistics in paleontology)?

Searching for lineages leads to a fallacy?

The idea that whithin a continental sedimentary succession a certain species occurring deeper than a related species should be regarded as the ancestor of the latter - unless disproven - always reminded of a type of logical fallacy called post hoc ergo procter hoc: "B occurred later than A, therefore A must be the reason for B." In terms of imposing the lineage concept: "Species B occurred subsequent to species A, therefore A must be the ancestor of B."

If a multiple- and irregularly branched bush is a good analogon to how evolution works I daresay the idea of a biostratigrapher to pick up the isolated fragements of branches (i.e. fossils) and glue them together in a few long continuous branches results in a bad model of the bush.

The problems occur after I have established a biostratigraphic zonation concept on the basis of what I think is a lineage: Someone working on the same material puts the species of my 'lineage' into a cladistic analysis and finds that there is almost no concordance between the appearance date of a species and its likely phylogenetic position.

If I do agree that similarities/ dissimilarities in morphology, histology, behavior, etc. should form the basis of a classification and consider the data basis of the phylogenetic analysis as sufficient I will have to admit that my scheme has been proven wrong. Or else if I suppose that the data are not sufficient and I myself cannot add more then I will have to concede that my scheme is at least no more valid than the alternative.

Proving microevolution depends on the sufficiency of "population" samples?

Im not saying that it is impossible to find arguments in favor of an ancestor-descendant relationship: Imagine I have large enough sample of specimens of the supposedly related species A, B, and C from three successive horizons. For A, B, C the empiric distributions of morphological parameters can be compared:
If the mean value & variance for A is not signficantly distinct from the mean and variance of B and
if the mean value & variance for B is not signficantly distinct from the mean and variance of C
but given a significant difference in the mean values/ variances of A and C,
I could infer that from A to C microevolution took place...
...but do we have such samples, let's say for tetrapods?

An example: Amphibian Biostratigraphy

These problems have been discussed for the amphibian biostratigraphy of the European Permocarboniferous as developed by Werneburg and Schneider and applied for various amphibian occurrences, see for example:

R. Werneburg & J.W. Schneider, 2006, Amphibian biostratigraphy of the European Permo-Carboniferous. In: S.G. Lucas, G. Cassinis and J.W. Schneider, Editors, Non-Marine Permian Biostratigraphy and Biochronology: Geological Society of London, Special Publications 265 (2006), pp. 201–215. [Link]

R. Werneburg, A. Ronchi, and J.W. Schneider, 2007, The Early Permian Branchiosaurids (Amphibia) of Sardinia (Italy): Systematic Palaeontology, Palaeoecology, Biostratigraphy and Palaeobiogeographic Problems. Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 252, Issues 3-4, 3 September 2007, Pages 383-404 [Link]

The zonation scheme and proposed lineages have been criticized by Steyer (2004) as being a stratophenetic rather than a true phylogenetic approach considering the criteria how the authors relate different species:

J. S. Steyer, 2004, Phylogenetic or stratophenetic systematics? - Comment of R. Werneburg: The branchiosaurid amphibians from the Lower Permian of Buxières-les-Mines, Bourbon l’Archambault Basin (Allier, France) and their biostratigraphic significance. Bull. Soc. géol. France, 2004, 175 (4), 423-425

Another particular problem is that amphibians are known to be abundantly subject to heterochronous evolution - evolutionary shifts in the ontogenesis, in particular, neoteny, is a common phenomen and can obscure characteristic features.

A recent analysis by Schoch & Milner (2008) on branchiosaurids, a group of neotenic small dissorophoid temnospondylians which is often considered for biostratigraphy, features a cladistic approach and proposes a scenario, related to which nodes of the tree neoteny/ life style changes occurred:

R.R. Schoch & A.R. Milner, 2008, The intrarelationships and evolutionary history of the temnospondyl family Branchiosauridae. Journal of Systematic Palaeontology (2008), 6 : 409-431 [link]

While the relationship of Branchiosaurus forming the outgroup of major clades (Melanerpeton-clade, Apateon-clade) is correspondent to the order of occurrences in the stratigraphic record, certain long ghost lineages occur - in particular the interpretation of Apateon gracilis/Melanerpeton gracile shows a mismatch between the cladistic approach of Schoch & Milner and the scheme of Werneburg & Schneider. This divergence is also the consequence of conflicting interpretations of the gracil(e/is) material, however, it demonstrates the potential for stratigraphic misinterpretation:

If I believe that a species forms the end member of a lineage because it is the youngest in certain sedimentary sequences I may underestimate the species' stratigraphic range - unlike the cladistic analysis which (if well-founded) would imply a deep divergence suggesting that some of the earlier record of the species is missing.

Decoupling (continental) biostratigraphic zonation from the lineage concept

Assuming that evolution works rather bush-like than lineage-like, I dont' see why we can't keep a biostratigraphic zonation even in the case of sparse continental records. I still can associate a series of morphologically defined taxa with a certain stratigraphic range and spatial distribution - until the concept has been shown not to be adequate (or not outside a more narrowly defined spatiotemporal window).

Whether it is a lineage-like relationship of species or another factor (related to geography, climate, ecology or else) that makes biostratigraphy work is a question which might be solved only in some cases.

Donnerstag, 14. Mai 2009

PALHERP Bonn 2009

The Meeting of the German Paleoherpetologists was launched in 1997 as an act of rebellion against the old mammal establishment which ruled the regular vertebrate workshops of the German Paleontological Society. A particular aspect of the Palherp is the relaxed atmosphere giving students the chance to present ideas and results without unfair senior criticism.

Last weekend the 13th Palherp meeting was held in Bonn. As the Steinmann Institute of Bonn University houses the German Research Foundation Unit on Sauropod Biology you can call it one of centres of paleoherpetology in Germany. Given the focus of the Bonn working group many of this year's presentations covered dinosaurs and/or bone histology.

Saturday: Martin Sander's keynote lecture on sauropod biology was followed by presentations on sauropodlet longbone histology, on rib histology and sauropod reproduction strategies.

The lower tetrapod session covered chroniosuchians, a pelycosaur jaw fragment as the earliest German amniote find, parareptiles and a basal diapsid.

In the afternoon a presentation on didactyle theropod footprints from the Oberkirchen Sandstone and a discussion of arguments/ phylogenetic analyses in favour of convergent flight origins in the Eumaniraptora followed. Furthermore a talk on finds from the Lower Muschelkalk of Winterwijk. H. Haubold discussed problems related to the continental P/T mass extinction event if it is taken as a dogma.

Sunday talks included the introduction of a new basal sauropod (from Niger), dinosaur palaeopathology, tooth morphology, isotope palaeontology, and 19th century history of dinosaur science.

Mittwoch, 18. März 2009

Fieldwork Photo of the Week

Madygen river oasis. Close to the point where the river cuts through a Paleozoic limestone massif (on the left), forming a deep gorge.

Samstag, 28. Februar 2009

Fieldwork Photo of the Week

Badlands of the SW outcrop area (Urochishche Madygen). Reddish colours mark the "Variegated Member" of the Madygen Formation. In the distance: tree tops of the Madygen river oasis.

Donnerstag, 19. Februar 2009

Fieldwork Photo of the Week

Colourful Jurassic strata. Who can see the unconformity?

Dienstag, 17. Februar 2009

Constructivist geoscience (II)

As a natural scientist you are disposed to believe that there is something on the outside of your consciousness, and also, that you as a human being have suitable means to investigate those things.

And there is the theory of critical rationalism and the praxis of how geoscience (and palaeobiology) is really done.

So what about the chronic underdeterminedness of geoscientific (and paleobiological?) models: Is the remaining uncertainty large enough to consider much of the geoscientific knowledge as mere constructs which are (forseeably) bad descriptions of real things?

The following list of sources of uncertainty and of other problematic points is without order, representing a collection of thoughts I had during one of those late night train journeys:

(1) Uncertainty from the misunderstanding of recently active complex processes (e.g. sediment transport by a river) used as model systems for ancient processes.

(2) Uncertainty from a lack of knowledge about the longterm consequences of currently active processes.

(3) Anactualistic processes (e.g. on Hadean earth; recovery after a meteorite impact).

(4) Selectivity of geological records and the variety of factors by which it can be governed.

(5) Equivocality of deeper earth investigation methods (geophysics, "1D" outcrops from drillings).

(6) Problems arguably associated with the "descriptive tradition of geoscience", which passes along varying ideas about the necessary exactness. There can be a certain disregard for matters of decision making, the question of how to choose a favourite hypothesis, the distinction between noise and information relevant for a problem.

(7) Plurality of fieldwork procedures [and other aspects of methodology], i.e. documentation methods in the field and the decision makings/ usuals paths of inference involved. Enhanced by national/ language boundaries - there can be different schools, sometimes failing to communicate.

(8) Choice of model systems: Due to the complexity of the matter we are choosing well understood model systems, but the comparability is overestimated in the specific case.

(9) Overuse of a canon of "inherited" procedures, which lead to systematic misunderstandings or put constraints on thinking (e.g. the drawing of sedimentary logs).

(10) Metamodels and metatheories (e.g. global palaeoclimate models, supertrees) may be particular problematic in geology/palaeontology as historical sciences. There may be so various data and multiple steps of inferences that circularities are hard to avoid and/or the question is, of how much value the insight from the model is.

(11) Bad integration of data in multidisciplinary approaches, if the model assumptions on which the integration is based are not well considered.

(12) Overinterpretation as a notorious phenomenon in geoscience, coming from the chronic paucity of data, the community's failure of encouraging modest/ honest claims.

(13) Unsystematic or right-out defective handling of temporarily or principially not-available data. (Hypothesis hinges to a considerable degree on the missing data - though you as the inventor are saying the solution of the problem is only a matter of effort.)

(14) As in other sciences: the dealing with falsifying data. As your object is so complex, you as geoscientist may always find an exception demonstrating that you are not (so) wrong.

(15) Underuse of quantitative approaches, another relic from earlier times of geosciencemaking.

(16) Changing accessibility of important outcrop areas (but also archives) limits falsifiability of hypotheses.

(17) Misinterpretations from reducing/ enlarging the dimensionality of a problem in an inference step (e.g. reconstructing a time series of 3D models from a number of 1D sedimentary logs). Not always considered: There is not necessarily a proportionality between the time span of a process and the volume of "waste" it creates or deletes.

(18) Downscaling, if done without reflection/ definition of the way of doing, can reduce the reproducability/ comparability.

(19) Thinking in cyclicities and the tendency to infer cyclic processes although their support is poor.

(20) Misconception about what the data are and where the interpretation begins. One might think this is only a beginner's mistake in geoscience - however, it may happen as well on a higher level if you have multiple stages of inference.

(21) Thinking in categories as though they represent something natural which is not defined by the observer (e.g. genus, family in biological systematics; stage, era in chronstratigraphy).

So, look critically at your own models in geoscience (and paleobiology). Are they well constructed?

Freitag, 13. Februar 2009

Permotriassic entomofaunal change + the Madygen

Dmitry E. Shcherbakov from Moscow is one of the paleobiologists studying the very group of beings for which Madygen really is a lagerstätte: insects.

Some of his 2008 papers in the Moscovian Paleontological Journal and Alavesia, a relatively new journal for fossil insects, can be found as .pdfs on the library page of the International Palaeoentomological Society (IPS).

Shcherbakov, D.E. 2008. Insect recovery after the Permian/Triassic crisis. Alavesia 2: 125-131. [pdf]

Shcherbakov, D.E. 2008. On Permian and Triassic insect faunas in relation to biogeography and the Permian–Triassic crisis. Paleontological Journal 42 (1): 15-31. [pdf]

The Alavesia paper outlines a three phase development of Triassic entomofaunas, beginning with
(I) a low-diversity episod of P/T recovery dominated by Paleozoic insect groups, followed by
(II) a summit phase with typical Triassic taxa in the Anisian-Carnian, and, with a decline in diversity, ending in
(III) a phase dominated by Late Mesozoic elements, especially featuring new aquatic insect groups.
Shcherbakov suggests, that each of the transitions began in the humid low latitudes and occurred later in the higher latitudes, i.e. the boundaries between those three stages are diachronous.

In the Paleontological Journal paper Dmitry Shcherbakov looks at the insect diversity of Late Carboniferous to Triassic localities, counting the proven occurrences of insect families per stage ('stage' as a chronostratigraphic unit). He illustrates the change in aquatic/ terrestrial, phytophages/ predators, modern/ ancient groups and explains the ecological, evolutionary, and biogeographic background of diversity fluctuations.

Shcherbakov, D.E. 2008. Madygen, Triassic Lagerstätte number one, before and after Sharov. Alavesia 2: 113-124.[pdf]

This review paper begins with a recount of the research history of the Madygen Formation as a Triassic fossil locality, beginning with the geological fieldwork in the 1930s (by Kochnev) which led to the first finds of a fossil flora, classified as Triassic, and to the introduction of the Madygen strata as a separate stratigraphic unit.

In detail the role of paleoentomologist Alexander G. Sharov is recognized, who lead five field expeditions between 1962 and 1966 to a fossiliferous point in the northern Madygen outcrop area (Dzhailoucho). These campaigns turned out as the most successful with regard to the number of recovered insect specimens and other fossils. The historical part is followed by a short overview of the flora and non-insect fauna.

The main part is a synopsis of the particular insect fauna of Madygen. Besides the exquisite state of preservation, several figures illustrate why Madygen really is a lagerstätte: Members of twenty insect orders and 96 out of 106 insect families known from the Ladinian/Carnian have been reported from the Madygen Formation.

In this order beetles, cockcroaches, and homopterans represent the most abundant groups. Among rarer groups are certain specialities, such as the most diverse assemblage of titanopterans. Modern insect orders are represented by several groups of early dipterans and the earliest hymenopterans (belonging to the group of sawflies).

Donnerstag, 12. Februar 2009


In memory of Charles R. Darwin (1809-1882)

My fish is sad and lonely
Striving for arms to embrace only
O Lamarck, the flesh is weak!
The fins just stay-
Despair 'n' dismay.

See generations later
Arms had but the best wade-through raider.
Fish feelings selection not passed.
They ebbed away-
Despair 'n' dismay.

Nothing but comprehension
Lies in Darwin's more stately mansion
World tells no moral'ty tale.
No more to say-
Despair 'n' dismay.

Montag, 2. Februar 2009

Fieldwork Photo of the Week

In the back you can see a tectonic contact: Massive limestones are thrusted over some less competent schist units and/or Madygen sediments. Thanks to Juliane for that photo.

Freitag, 23. Januar 2009

Triassic critters: Freshwater sharks

Lakes and rivers of the younger Paleozoic and as well in the Triassic could not only house tetrapod and bony fish vertebrate dwellers but also selachian predators, in particular the Xenacanthida, well known for their characteristic neck spines, and the Hybodontiformes, which display a pair of lateral head spines and characteristic fin spines. The latter are distinct from those of the Acanthodii (popularly also referred to as "spiny sharks"), a group of basal vertebrates that ocurred in freshwater environments as well, but became extinct before the beginning of the Triassic.

Complete shark specimens are seldom recorded, the same is true for complex finds comprising a couple of skeletal elements from the same individual - taxonomists often have to deal with assemblages of individual scales, spines, and teeth and systematics heavily relies on tooth characteristics (e.g. Schneider 1988 for the Xenacanthida, Rees 2008 for hybodont sharks).

Like the recent bullhead sharks (Heterodontus) at least some of the Carboniferous to Triassic freshwater sharks were oviparous - different types of spiral egg capsules not quite unlike those capsules of Heterodontus occur in different types of freshwater environments, e.g. marginal lake sediments or low-energy river banks; often they appear unrelated to skeletal remains. This has been interpreted as being indicative for a separation between the actual habitats of the sharks and their spawning grounds (about the facial aspects: see Schneider & Reichel 1989). To what extent the occurrence of xenacanth and hybodont sharks in freshwater deposits is indicative for a marine influence is currently a matter of debate.

In the first descriptions of the 19th century fossil egg capsules were misinterpreted as cone-like fructifications of some kind of plant. This was due to the rhomboidal pattern the egg capsule impressions often display as consequence of taphonomic flattening (and the consequent overlap of the spiral patterns on the front and back sides). Two types of shark egg capsules have been recovered from the Madygen Formation during fieldwork in 2007 (Fischer et al. 2007) - more on that later.

Jan Fischer, featured in the last FPhotW, who is working on the Madygen chrondrichthyans (as soon as they appear) and isotope paleontology of shark teeth/spines, is thanked here for supplying me with literature. (Hopefully I can convince Jan to write a guest contribution).


Synoptical papers:
Maisey, J.G. (1982): The Anatomy and Interrelationships of Mesozoic Hybodont Sharks. - American Museum Novitates 2724: 1- 48; New York.

Schneider, J. W. & Zajic, J. (1994): [Xenacanths (Pisces, Chondrichthyes) of the middle European Upper Carboniferous and Permian - revision of the originals of GOLDFUSS 1847, BEYRICH 1848, KNER 1867 and FRITSCH 1879-1890.] - Freiberger Forschungshefte, C 452: 101-151; Leipzig.

On tooth systematics:
Schneider, J.W. (1988): [Basics of the morphogeny, taxonomy, and biostratigraphy of isolated xenacanth teeth (Elasmobranchii)]. - Freiberger Forschungshefte, C 419: 71- 80; Leipzig.

Rees (2008): Interrelationships of Mesozoic hybodont sharks as
indicated by dental morphology – preliminary results. - Acta Geologica Polonica 58 (2): 217-221.

On egg capsules:
Schneider, J.W. & Reichel, W. (1989): [Chondrichthyan egg capsules from the Rotliegend (Lower Permian) of Middle Europe - conclusions regarding the palaeobiogeography of palaeozoic freshwater sharks.] - Freiberger Forschungshefte, C 436: 58- 69; Leipzig.

Fischer, J., Voigt, S. & Buchwitz, M. (2007):
First elasmobranch egg capsules from freshwater lake deposits of the Madygen Formation (Middle to Late Triassic, Kyrgyzstan, Central Asia). - Paläontologie, Stratigraphie, Fazies (15), Freiberger Forschungshefte, C 524: 41-46; Freiberg.

Mittwoch, 21. Januar 2009

Fieldwork Photo of The Week

Morning time at the digging site: Having contemplated the vast landscape bare of human presence but sprenkled with the litter of a forgotten civilization graduate student Jan Fischer decides on the right moment for starting his daily business of not moving to many a rock at once and feigning the impression of having survived another day in this vale of tears only at the close of livelong fatigue and exhaustion...

Mittwoch, 7. Januar 2009

Fieldwork Photo of the Week

See the spy in the back? Some Kyrgyz aborigines can't help being distrustful...

I'm thankful to Juliane Hentschke who safed us these moments and a number of bones.

Samstag, 3. Januar 2009

Tectonics & Paleo (4):
The world of CPOs and ODFs

Materials in geoscience and biology are often not isotropic - their properties, such as conductivity, soundwave velocity, and shear strength, vary with direction.

The reason can be that they are crystalline - if so, the orientation of the crystal lettice of (one, a few, or) many individual crystal grains has an influence on the properties of the compound material. The individual crystal lettice orientations can be at random or their can be a preferred orientation.

A whole branch of mineralogy and material science deals with the analysis of materials which show crystal preferred orientations (CPOs).

From Tectonics...

Structural geologists, who are dealing with microscopic phenomena of tectonic deformation, use mineral textures of rocks, i.e. crystal preferred orientations of the rockforming minerals, as indicators of tectonic movement and deformational regimes (temperature, pressure conditions; deformation rate).

The so-called Orientation Distribution Density Function (ODF) describes how the crystal axes of mineral grains in a sample are oriented relative to an outer coordinate system (e.g. geographic XYZ coordinates). From the ODF, usely depicted as a couple of stereographic density plots (e.g. plots for the crystal a-axis, b-axis and c-axis orientations) the direction and sense of shearing of a rock can be inferred. Paleontology

Not only tectonic forces are governing the crystalline properties of natural materials. In a similiar way the (often monomineralic) mineralized tissues of organisms are underlying specific biological formation conditions - the different layers of a skeleton can show rather perfect CPOs.

Crystal orientations in mineralized tissue are, of course, not defined relative to a geographic coordinate system but to the anatomic directions (or the axis of accretionary growth) of the animal as a reference system.

Coming from the tectonical side I was participating in a workshop on "Textures & Microstructures in Geosciences" in 2005: I was really surprised that there is an application of texture analysis in palaeontology and that some people are really doing it.


You can do either single grain measurements or methods integrating all orientations of crystal grains in a certain volume of the sample.

U-stage and EBSD are involving single grain measurements of a thin section: For each grain in a certain raster the individual crystal orientation is determined - either by its optical properties using the universal stage (this old-fashioned manual method is rather time-consuming) or by the way how electrons from an electron microbeam are backscattered on a detection screen (Electron Backscatter Diffraction, EBSD). The detected Kikuchi line patterns are indicative for how an individual crystal is oriented (they can be interpreted automatically). What you get in both approaches is not only an ODF but also a crystal orientation map of your thin section.

XRD, Neutron Diffraction. In these methods an X-ray or neutron beam is used to measure a larger volume of a sample comprising several crystals, thereby neutron radiation can penetrate even larger samples completely while the X-ray has a relatively low depth of penetration. From the detected line sprectra pole figures, representing the distributions of certain crystal lettice plane orientations can be derived (from which in turn the ODF of all the crystals in the measured sample volume can be deduced).

Examples from Paleontology

Chateigner, D., Hedegaard, C. & Wenk, H.-R. (2000): Mollusc shell microstructures and crystallographic textures. - Journal of Structural Geology 22: 1723-1735.

The authors employ X-ray diffraction measurements and demonstrate thate the microstructures and crystallographic textures of aragonite layers of species from different mollusc taxa including bivalves, cephalopods, gastropods and monoplacophorans are highly specific and contain a phylogenetic signal: closer relatives are more similar in their shell's crystal orientations.

Pyzalla, A.R., Sander, P.M., Hansen, A., Ferreyo, R., Yi, S.-B., Stempniewicz, M. & Brokmeier, H.-G. (2006): Texture analysis of Sauropod bones from Tendaguru. - Material Science and Engineering A 437: 2-9.

This neutron diffraction approach addresses the question whether the apatite crystallite textures in adolescent and adult Brachiosaurus long bones show some signal indicative for specialized crystal orientations which can be attributed to the giant growth of sauropod dinosaurs. However, comparing their results to the measurements of turkey and other dinosaur long bones they found no significant difference in texture strength or in the predominant direction of fibres.


Given the elaborateness of most approaches, measurements of crystallographic textures are rarely used in paleontology - I suppose this will change if it turns out that the analysis of the crystal orientations can provide substantial information which is not obtained from the usual analysis of skeletal histology and microstructures.

Donnerstag, 1. Januar 2009

Happy Darwin Year!

Coming to us in 2009: festivities and colloquia celebrating the 200th birthday of Charles Darwin and the 150th anniversary of his grand oeuvre

On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life,

which was "introducing sense into biology" (badly corrupted from the Ernst Mayr quote).

Looking back a palaeoherpetologist would call 2008 the year of the turtle:

With the descriptions of Odontochelys and Chinlechelys and some further contributions (a list is provided by N. Gardner) the origins of turtles were greatly enlightened.

This topic was variously covered by the pal(a)eo and evo blogs – see for example here and here (Bill Parker's Chinleana) or here and here (Adam Yates' Dracovenator blog).

BTW: How many recent On-papers do you know?

What is the right occasion to start a contribution with 'on'? Did you ever think about it ... to me such a beginning suggests a long-winded reflection of/ a comment on sth. rather than focusing on the presentation of new data.

The Twelve Days of (Paleo) Christmas are not yet over - you are still welcome to participate in the poll. >>>>>

I support Scientific Triassicism! An initiative by Neil from Microecos. What do you think: Is 'Triassic Science' or 'Triassology' a sexier term?

(How long one week and a half can be: I forgot how to compose a text, that's why this post is only a list of notes.)