Madygen bryophytes and lycopsids

Moisan, P., S. Voigt, J. W. Schneider & H. Kerp. 2012. New fossil bryophytes from the Triassic Madygen Lagerstätte (SW Kyrgyzstan). Review of Palaeobotany and Palynology 187:29–37. [Abstract]

Recent paper on liverworts and leafy mosses from the Madygen Formation. Adds some new aspects about the Madygen flora which is known for its diversity of seed ferns, lycopsids, horsetails, and cycadophytes whereas (unambiguous) fossils of non-vascular plants, some of them occurring densely packed in shallow lacustrine sediments (and possibly represent submerged plants of the lake margin), have been described for the first time by Moisan and colleagues.

Moisan, P. & S. Voigt. 2013, in press. Lycopsids from the Madygen Lagerstätte (Middle to Late Triassic, Kyrgyzstan, Central Asia). Review of Palaeobotany and Palynology. [Abstract]

Revision of the Madygen lycopsids and of the problematic "Longisquama-appendage-like" foliage Mesenteriophyllum based on materials excavated between 2006 and 2009 whose macromorphological and microscopic epidermal features were studied. Originally described by Sixtel (1961) as a new genus of gymnosperms, Mesenteriophyllum-like plants are now found to belong to different higher lycopsid taxa (Pleuromeiales, Isoetales).

Insect-plant interaction in the Madygen forest

Philippe Moisan, who defended his Ph.D. thesis on floral remains from the Madygen Formation earlier this year, is main author of a recently published paper on ovipostion damage:

Moisan, P., C. C. Labandeira, N. A. Matushkina, T. Wappler, S. Voigt, and H. Kerp (2012): Lycopsid–arthropod associations and odonatopteran oviposition on Triassic herbaceous Isoetites. Palaeogeography, Palaeoclimatology, Palaeoecology 344–345: 6–15. [Link to abstract]

Describes an oviposition damage pattern typical for dragonflies on the quillwort Isoetites which is an unusual thing because lycopsids were not yet known to be hosts of dragonfly egg-laying.

The Longisquama paper in press got some media coverage

Science writer Jeff Hecht wrote an article discussing results of our study:

Jeff Hecht: Reptile grew feather-like structures before dinosaurs. New Scientist, issue 2857, 23 March 2012.

Was a bit afraid of this, because often a finely nuanced statement is cited incorrectly or even turned into the opposite when the message of a paper is adapted for a non-specialist audience. Looks okay, though.

New papers on Kyrgyzsaurus, Madygenerpeton, and Longisquama

Alifanov, V. R. and E. N. Kurochkin. 2011..Kyrgyzsaurus bukhanchenkoi gen. et sp. nov., a new reptile from the Triassic of southwestern Kyrgyzstan. Paleontological Journal 45(6):639-647.
[DOI: 10.1134/S0031030111060025] [link]

Description of a reptile fossil with skin preservation discovered in 2006. Comes form the same locality as Sharovipteryx and Longisquama. The authors interpret the specimen as a member of drepanosaurs, a Late Triassic group of archosauromorphs. This paper represents one of the last contributions of the Russian palaeornithologist Evgenii N. Kurochkin who passed away recently.

Buchwitz, M., C. Foth, I. Kogan, and S. Voigt. 2012 in press. On the use of osteoderm features in a phylogenetic approach on the internal relationships of the Chroniosuchia (Tetrapoda: Reptiliomorpha). Palaeontology. [DOI: 10.1111/j.1475-4983.2012.01137.x] [link]

Includes a graphic reconstruction of Madygenerpeton (drawing by Frederik Spindler).

Buchwitz, M. and S. Voigt. 2012 in press. The dorsal appendages of the Triassic reptile Longisquama insignis: reconsideration of a controversial integument type. Paläontologische Zeitschrift.
[DOI: 10.1007/s12542-012-0135-3] [Link]

More thorough description/ graphic documentation compared to Voigt et al.(2009) and considers some aspects of diapsid skin evolution.

Madygen freshwater sharks made the JVP front page

Fischer, J., S. Voigt, J. W. Schneider, M. Buchwitz & S. Voigt (2011): A selachian freshwater fauna from the Triassic of Kyrgyzstan and its implication for Mesozoic shark nurseries. Journal of Vertebrate Paleontology 31: 937- 953. [Abstract]

Aha: Egg capsules and microvertebrate fossils can be a worthwile study object after all. (Event though Jan Fischer, my fellow grad student at the Geological Institute in Freiberg, had an interview with a critical local newsreporter who doubted that anybody could ever be interested in something like that.)

Jan and colleagues describe chondrichthyan egg capsule fossils from the Madygen Formation and refer them to Palaeoxyris, a capsule type usually assigned to hybodont sharks, and Fayolia, probably produced by xenacanth sharks. These fossils are accompagnied by nearby finds teeth of hybodont shark teeth - most of them are tiny and probably belonged to juveniles of the newly erected species Lonchidion ferganensis.

Oxygen isotope analysis of the teeth and their comparison to hybodont teeth from other localities yields a clear freshwater signal for the Madygen samples, indicating that the shark offspring indeed inhabited a freshwater habitat.

Facial analysis of the sedimentary succession of the Madygen Formation demonstrates the presence of wide-spread shallow and vegetated shore areas during the Middle Triassic which could have functioned as a shark nursery, i.e. a separate and ecologically distinct habitat for juveniles which was not invaded by adult sharks of the same species.

Triassic cicadomorph insects with camouflage

Shcherbakov, D. 2011. New and little-known families of Hemiptera Cicadomorpha from the Triassic of Central Asia – early analogs of treehoppers and planthoppers. Zootaxa 2836: 1-26. [article preview with abstract]

Dmitry Shcherbakov describes twelve new (monotypic) genera and species of cicadomorphs from the Madygen Formation on the basis of some exquisitely preserved fossils and redescribes three others.

He finds homoplastic similarities of the fossil families Saaloscytinidae and Maguviopseidae (newly erected) to leaf hoppers and tree hoppers (Membracoidea) and of Mesojabloniidae to plant hoppers (Fulgoroidea)

Convergent to the extant groups of cicadomorphs the newly described fossil taxa use different means of camouflage, namely bizarrely-shaped tegmina (singular 'tegmen' = anterior cover wings without aerodynamic function), dorsal projections on the thorax and tegmen, well-developed surface sculpture, and (dull) coloration. According to Shcherbakov the specific morphology of the Maguviopseidae and Saaloscytinidae mimicked thorns, bracts, seed-bearing organs, seeds, buds, or leaves, whereas the Mesojabloniidae mimicked rotten wood or bark.

Shcherbakov assumes that predation by tree-living reptiles, such as Sharovipteryx and Longisquama (which are known from the same locality within the Madygen Formation), was an important factor underlying the evolution of elaborate types of camouflage.

As none of these Triassic hoppers appear to have survived for long, Shcherbakov concludes that their extinction was linked to the extinction of the host plants whose plant organs they imitated.

A palaeodictyopteran and other relics from Madygen

Béthoux, O., S. Voigt, and J. W. Schneider. 2010. A Triassic palaeodictyopteran from Kyrgyzstan. Palaeodiversity 3: 9-13. [pdf 1.5 Mb]

Despite the substantial collection and study of insect fossils from the Madygen Formation (see overview in Shcherbakov 2008a) there are still unkown elements of the entomofauna left. Béthoux et al. (2010) describe a wing of a not yet reported group of insects from lacustrine shales of the northwestern ouctrop area of the Madygen Fm. (which also yielded Sharovipteryx and Longisquama).

Ruling out all alternatives on the basis of wing venation data, they come to the conclusion that reliquia spec. nov. was a late member of Palaeodictyoptera, an order-rank group according to conventional classification schemes that was previously thought to have died out during the Middle or Late Permian.

Béthoux et al. suggest that the disappearance of ancient insect groups in equatorial realms is linked to the Late Paleozoic aridisation in these areas that triggered the migration to wetter higher latitude ecosystems, such as the Madygen lake environment. The relatively late occurence of paleodictyopterans in Madygen is also in agreement with Shcherbakov's (2008b) hypothesis that the renewal of Triassic entomofaunas was asynchronous, starting in the lower latitudes and spreading to the higher latitudes.

Other Madygen relics?

Apart from modern groups, such as dipterans and hymenopterans among insects as wells as lissamphibians and archosaurs among tetrapods there are further relict forms, such as the choniosuchian Madygenerpeton or the basal cynodont Madysaurus. As hinted by Béthoux et al. the question to what degree and why Madygen functioned as a refugium is still to be answered.

Chroniosuchia: Paper on osteoderm histology in online preview

...my first experience with bone histology:

Buchwitz, M., Witzmann, F., Voigt, S. & Golubev, V. in press. Osteoderm microstructure indicates the presence of a crocodylian-like trunk bracing system in a group of armoured basal tetrapods. Acta Zoologica, DOI: 10.1111/j.1463-6395.2011.00502.x

Abstract. The microstructure of dorsal osteoderms referred to the chroniosuchid taxa Chroniosuchus, Chroniosaurus, Madygenerpeton and cf. Uralerpeton is compared to existing data on the bystrowianid chroniosuchian Bystrowiella and further tetrapods. Chroniosuchid osteoderms are marked by thin internal and relatively thick external cortices that consist of lowly vascularised parallel-fibred bone. They are structured by growth marks and, in case of Madygenerpeton, by lines of arrested growth. The cancellous middle region is marked by a high degree of remodelling and a primary bone matrix of parallel-fibred bone that may include domains of interwoven structural fibres. Whereas the convergence of Bystrowiella and chroniosuchid osteoderms is not confirmed by our observations, the internal cortex of the latter displays a significant peculiarity: It contains distinct bundles of shallowly dipping Sharpey’s fibres with a cranio- or caudoventral orientation. We interpret this feature as indicative for the attachment of epaxial muscles which spanned several vertebral segments between the medioventral surface of the osteoderms and the transversal processes of the thoracic vertebrae. This finding endorses the hypothesis that the chroniosuchid osteoderm series was part of a crocodylian-like trunk bracing system that supported terrestrial locomotion. According to the measured range of osteoderm bone compactness, some chroniosuchian species may have had a more aquatic lifestyle than others.

Maths in Paleontology (I): Data

''In every special doctrine of nature only so much science proper can be found as there is mathematics in it.'' - Immanuel Kant, Metaphysical Foundations of Natural Science (1786)

Warningly the maths professor who got the unthankful task to teach us first-semester scientists-to-be some basic basics of his field chose Kant's statement as the first in his first lecture on "higher" maths. However, when I started my studies in geology and paleontology, there was another saying among old school geology teachers: "A bad mathematician makes a good geologist."

Many a fellow student were rather willing to believe in these latter words than in the inconvenient alternative. (I always considered this believe as outdated and I got the feeling that geology as a science might have been shaped not only by the talents of its protagonists but also by their limitations in terms of exactness and rigorousity.)

Luckily you were not necessarily considered as a bad geologist if you were interested in maths and the notion that modern geoscience involves maths and exact methods (e.g. methods of quantitative data analysis, databases, multivariate statistics and geostatistics, geoinformatics and geographic information systems, 3D and 4D modelling, remote sensing) was clearly on the rise. Perhaps from a biologists' point of view this story would be different, but, to tell you the truth, some of the biology-based paleontologists I got to know are not much living on the exact side either.

Apart from microscopy seminars, field, and lab practicals which teach you ways of data acquisition some classes in statistics and data analysis during first semesters of study give you an idea about the structure of data and ways how to sample and how to deal with data in order to find new knowledge, e.g. a relationship between two phenomena previously not considered to be related.

At the very beginning you will learn that there are different types of data used in paleontology and that you have to bring your data into shape for any kind of mathematical analysis tools, i.e. arrange them as a data table such as the following:

Specimen	Class	State of XYZ	No. of UVW	size L [mm]	size M [cm²]
A	a	Aa	2	12.1	234
B	b	B	3	13.3	87
...	...	...	...	...	...
X	x	X	...	...	...

Normally lines of the table represent samples (or groups of samples or taxa) whereas columns may represent various features or measures. Such features may be the belonging to a certain class or category or the presence, absence, or specificity of a feature. Measured values as entries may have a discrete contribution (e.g. natural numbers such as the number of teeth or segments or body chambers) or a continuous distribution (e.g. length, area, angle, temperature measurements).

Various data relevant for paleontologists can be arranged as tables, such as morphological and microstructural data, stable isotope and other geochemical data, geographical, sedimentological, and stratigraphic data, as well as taphonomic and paleoecological data. Some of these data have a special structure and can be referred to one of the following types:


Compositional data...

... add up to 100%. Chemical compositions of fossils or faunal compositions are compositional data:

Community	Trilobites	Brachiopods	Echinoderms	Poriferans	Nautiloids
A	23 [%]	42	17	5	13
B	10	15	5	50	20
...	...	...	...	...	...
X	...	...	...	...	...

These data require careful considerations and a special kind of maths because all variables are (necessarily) correlated and thus an alleged dependence, e.g. of brachiopod and echinoderm abundances, can be obscured by variation in another group.


Spatially or temporally correlated data

‘Spatial correlation’ means that values for data points close to each other are more similar than values of more distant data points – e.g. the faunal composition of an ecosystem from Arizona is rather like that of a Nevada community than that of a Massachusetts community.

Locality	Easting (X)	Northing (Y)	Facies	Archosaurs [%]	Rhynchosaurs [%]
A	5687	0487	lacustrine	23	45
B	6485	0808	fluviatile	34	38
C	6800	1490	fluviatile	40	37
...	...	...	...	...	...

Geostatistics is the usual method to deal with spatially correlated data. Spatial correlation can also occur on much smaller scales, e. g. the shape and size of two skull bones in contact to each other can show a stronger dependence than the shape and size of bones that are more distant to each other.

In paleontology temporal correlation is quite abundant, especially if your study considers different stratigraphic ages or sedimentological field data:

Population	Horizon	Ar/Ar age [Ma]	Facies	δ18O [‰]	Average size [mm]
A	1	210 ± 1	deltaic	-2.0	5.2
B	2a	N/A	distal shelf	1.4	6.4
C	2c	207 ± 2	?	2.1	6.8
D	4	200 ± 1	deltaic	-2.2	6.0

As in stockmarket analytics methods of time series analysis can be applied to interpret temporally correlated data (i.e. time series). Such data may be relevant for your study as they often indicate evolutionary trends (biological evolution in the stricter sense but also evolution of paleoenvironments), cyclic processes with a certain periodicity, and/or they can form the basis for relating contemporaneous processes in the geological past (e.g. stratigraphic correlation of separate sedimentary successions).


Orientation data

For elongated fossils such as conical shells or long bones the orientation of the fossil long axis towards the geographical cordinate system can be measured using a compass (with inclinometer). In a similar way the orientation of bedding planes can be documented. Such measurements are often used for the purpose of deducing the former transport direction of a ancient sediment transport and depostion system (such as a river, delta, or alluvial fan). A data table with orientation data may look like that:

Specimen No.	Description	Length [cm]	Horizon	Azimuth>	Dip
1	long bone	21	1	N 20° E	0°
2	rib	12	1	N 10° W	5°
3	calamite stem	80	2a	N 15° E	0°
...	...	...	...	...	...

“Azimuth” refers to the angle towards north. Orientation data are distributed on a halfsphere. Mean values (e.g. the average orientation of long bones) and other distribution parameters cannot be derived directly from the averaging of orientation angles but vector arithmetics has to be applied.


Cladistic data

Phylogeny on the basis of morphology conventionally involves cladistic methods, especially in the field of vertebrate paleontology which deals with a particular character-rich group that is deemed suitable for cladistic approaches employing certain kinds of analysis software specialized for the calculation of phylogenetic trees (e.g. PAUP, WinClada).

In cladistic datasets lines represent taxa, mostly species or genera of the group of interest, and columns represent characters (ordered by number), i. e. features of the skeleton which are variable among the included taxa:

Taxon	1	2	3	4	5	6	7	8	9	10
A-saurus	0	0	0	0	0	0	1	0	?	0
B-raptor	?	0	1	?	0	0	1	1	0	0
C-onyx	1	1	0	?	-	1	-	1	0	1
D-ops	1	1	2	1	1	1	1	0	1	1
E-mimus	0	-	2	1	1	2	0	0	1	1

One of the main issues in cladistics is the definition of characters and the correct (unbiased) coding of morphological information. You can include qualitative differences ("bone X contacts bone Y but not bone Z" = character state “0”; "bone X contacts bones Y and Z" = character state “1”) and quantitative differences ("length of metatarsal 3 larger than or as large as length of metatarsal 4" = character state "0"; "mt3 is shorter than mt4" = "1"). Sometimes mixed character states like "0 or 1 [but not 2]" occur in a taxon and are coded accordingly.


Missing data...

...occur all the time in paleontology ... either because specimens are not complete enough or because their geological age cannot be exactly determined or because specimens are too rare or valuable to use them for a destructive analysis method or because they are for some reason no longer accessible. "N/A" ("not applicable") or empty entries or question marks often symbolize missing data.


Some introductory literature:

Borradaile, G. J. 2003. Statistics of Earth Science Data. Springer, Berlin, 280 pages. ISBN 3540436030

Swan, A. R. H. and M. Sandilands. 1995. Introduction to geological data analysis. Blackwell, Oxford, 446 pages. ISBN 0632032243

New paper on cycadophytes from Madygen

Moisan, P., S. Voigt, C. Pott, M. Buchwitz, J. Schneider, and H. Kerp. in press. Cycadalean and bennettitalean foliage from the Triassic Madygen Lagerstätte (SW Kyrgyzstan, Central Asia). Review of Palaeobotany and Palynology. [DOI:10.1016/j.revpalbo.2010.11.008]

Philippe Moisan who is doing his Ph.D. in Münster (with paleobotanist Hans Kerp as his supervisor) studies the flora of the Triassic Madygen Fm. In his first paper on that issue he introduces cycadophyte finds collected between 2005 and 2009.

Many of the studied the specimen come from the same succession and locality as Madygenerpeton (there is also a small sketch of the sedimentary profile, see Fig. 2).

One thing I learned from this study was that so-called "xeromorphic features", i.e. plant features that are usually the consequence of an adaptation to aridity, cannot only occur in xerophytes, i.e. in plants adapted to dry environments, but (for other reasons) in hygrophytic and halophytic plants as well.

Indications for aridity, such as desiccation crack horizons or or seasonally drying-out ponds and rivers or wide-spread red bed sediments are lacking in Madygen. Thus, according to Philippe's interpretation, "xeromorphism" in Madygen plants probably served other purposes than the xeromorphism of xerophytes (e.g. "self-cleaning of the leaf surface, regulation of excessive radiation and leaf temperature, mechanical defense against phytophagous insects").

Three recent papers on chroniosuchians

Buchwitz M, Voigt S. 2010. Peculiar carapace structure of a Triassic chroniosuchian implies evolutionary shift in trunk flexibility. Journal of Vertebrate Paleontology 30: 1697-1708. [Link]

Schoch RR, Voigt S, Buchwitz M. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnaean Society 160: 515-530. [Link]

Klembara J, Clack J, Čerňanský A. 2010. The anatomy of palate of Chroniosaurus dongusensis (Chroniosuchia, Chroniosuchidae) from the Upper Permian of Russia. Palaeontology 53: 1147-1153. [Link]

The redescription of the Chroniosaurus dongusensis palate by Klembara and colleagues adds further data to the morphological dataset provided by Clack and Klembara (2009) in their revision of C. dongusensis on the basis of a new specimen (which is the most complete of any yet known chroniosuchian). According to the updated phylogenetic analysis from the 2010 paper Chroniosaurus as the only included chroniosuchian taxon formed the sister group of embolomeres.

Schoch and colleagues (me included) describe Madygenerpeton pustulatus, a new species of chroniosuchians from the Middle to Late Triassic of Central Asia with a highly derived skull morphology and a carapace that was chroniosuchid-like in many aspects. The find shows that one lineage of chroniosuchids survived the Permian-Triassic boundary (by 20 or so million years).

The authors discuss characteristics uniting chroniosuchians with "higher reptiliomorphs" and unlike the approach of Klembara and colleagues their cladistic analysis, which includes five chroniosuchian taxa, results in a position of chroniosuchians somewhat closer to amniotes than to embolomeres. Chroniosaurus comes out as the closest relative of Madygenerpeton (both share the characteristic ornamentation of the skull and osteoderms besides other features).

Buchwitz & Voigt consider the functionality of chroniosuchian carapaces, comparing them to archosaur osteoderm systems. They argue that chroniosuchian carapaces basically served terrestrial locomotion but that the higher lateral flexibility of the Madygenerpeton osteoderm system was linked to a secondary increase in undulation swimming capability.

Reference:
Clack JA, Klembara J. 2009. An articulated specimen of Chroniosaurus dongusensis, and the morphology and relationships of the chroniosuchids. Special Papers in Palaeontology 81: 15-42. [Link]

Palges Meeting October 2010 in Munich

The 80 th Annual Meeting of the German Paleontological Society took place from the 6th through the 8th October 2010 within the halls of the Bavarian State Collection for Geology and Paleontology in Munich.

Of particular interest for me was the session on Early Mesozoic vertebrates chaired by the Rauhut couple and Richard Butler as it united many interesting characters, such as Silvio Renesto, Martin Ezcurra, Rainer Schoch, and Daniela Schwarz-Wings and covered a variety of Triassic vertebrates including archosaurs, temnospondyls, and bony fish.

With 5 talks and 6 posters our small Freibergian working group had quite a number of contributions this year (my prof Jörg Schneider was talking about Paleozoic cockroaches from China, Olaf Elicki about Cambrian trace fossils from Africa and the Middle East, Frederik Spindler about the evolution of haptodonts and other early synapsids, Jan Fischer about oxygen isotope signals in Permian and Triassic freshwater shark teeth and I had a talk on osteoderm histology and the Chroniosuchia). My colleagues Ilja Kogan and Jan Fischer won the 1st poster prize with their poster entitled "The Madygen lake deposits: A unique multi-taxa kindergarten for Triassic fisches" - which is quite an achievement as normally the winner comes from the host institute of the Palges Meeting.

The image on the right shows me in front of a poster entitled "Paleontology in the German Wikipedia" [pdf].

Even though there are many private collectors and paleontology enthusisasts in Germany, Austria, and Switzerland you won't find much about "regional paleontology" in the German Wikipedia which was the reason for my colleagues and me to introduce some aspects of Wikipedian (Pop-)Sciencewriting.

The poster praised the advantages Wikipedia can have if it is reasonably incorporated in public outreach campaigns and we commented critically on the dinosaur focus which increases the already biased public image of what paleontology is about.

Madygenerpeton pustulatus: first description finally out

Schoch, R. R., S. Voigt, and M. Buchwitz. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society 160(3): 515-530. [Abstract]

Madygen trace fossil paper

Voigt, S. and D. Hoppe. 2010. Mass Occurrence of Penetrative Trace Fossils in Triassic Lake Deposits (Kyrgyzstan, Central Asia). Ichnos 17:1-11. [Link]

Besides the exquisite soft body preservation of insects and tetrapods within some parts of the lacustrine succession, the Triassic Madygen lake shows a rich inventary of invertebrate trace fossils, studied by my colleague from Freiberg Sebastian Voigt.

The interesting point about these ichnofossil assemblages is that they demonstrate a certain differentiation of the lake ground in better and less well aerated zones, displaying different degrees of bioturbation and abundances of indicative ichnotaxa.

You can imagine that fresh water lake grounds only became inhabited stepwise after the conquest of land by animals, so these trace fossil assemblages mark a certain evolutionary level of lake ecosystems, otherwise rarely documented in detail from the Middle to Late Triassic.

Perception of deep time by geologists and biologists

Following the Darwin Year a colloquium lecture by zoologist Prof. Wolfgang Maier from Tübingen dedicated to "Darwin and deep time" discussed Charles Darwin’s role as a geologist who (among others) introduced the concept of deep time (a term later coined for million to several billion year long time ranges in geology) to biology.

Darwin did this by translating a hierarchy of (anatomical) similarity into a tree scheme that linked organisms from successive time slices with thousands of generations separating each two slices (see the scheme from Darwin’s "Origin of Species": [link]). The time slices can be related to certain units of the geological time scale.

Deep time correspondents in stratigraphy …

The problem of imagining time ranges far outside the scale of human experience has been approached by geologists with the method and concepts of stratigraphy: Strata of rock can be interpreted as a succession of time slices. Relative ages and age differences often manifest in an amount of rock which is loosely corresponding to certain a time span if similar rockforming processes are underlying. The relationship between the duration of a process and the amount of materal it creates can be inferred from direct observation of recent systems, allowing the assignment of absolute time (in years or millions of years) to a succession of strata. Given that long-term geological processes are rarely gradual, a more reliable absolute age is provided by radiometric dating.

If you would ask a geologist how he/ she percieves deep time I suppose he/ she would explain that it becomes clear from the slowness of present-day geological processes on the one hand and from the vast amount of products of such processes on the other hand.

… and phylogenetics

The evolution of organisms yields another approximation of deep time: The passing of time manifests in the hierarchical distinctness of living systems. Seeing how slow evolution works in a human being’s life span and how much change in anatomy/ biochemistry etc. must have occurred since last common ancestor of mouse and elephant or of mouse and lemon tree, leads to another way of percieving long time spans.

Regarding a certain distinctness and species richness of a group as a product of a certain number of character changes and speciation events (which is more or less well correlated with time) was probably enhanced by the more quantitative look at phylogenetics since the introduction of cladistics and molecular methods.

When I was attending a workshop on molecular paleobiology in 2008 specialists of that field were using the expression “(addressing) deep time problems” synonymous to phylogenetics of higher systematic groups, i.e. as the study of evolutionary changes that occurred deep down in the tree of animals and other organisms – opposed to let’s say the comparative analysis of human and neanderthal genomes or the radiation of Darwin finches.

The viewpoints of paleontologists…

But how do (present-day) paleontologists percieve deep time? You would expect them to share the view of both, phylogeneticists and stratigraphers, as most of them are taught at least a bit about both fields. However, for a paleontological fieldworker who employs the study of fossils as a means to understand and describe geological processes and paleoenvironmental contexts the flow of time is much easier grasped as a series of events preserved in a succession of rocks (and not as a phylogenetic tree scheme).

On the other hand, as a consequence of the so-called paleobiological revolution, you don’t need to be a field worker to contribute to the understanding of ancient organisms. In fact many aspects of paleobiology require mere laboratory and magazine work and you can spend a lifetime on that without ever considering rocks – naturally the perspective of such a modern paleobiologist on deep time will be strictly that of a phylogeneticist.

…can lead to conflicts?

These different perceptions on deep time and evolution are probably the background why cladistics was (and still is) met with some scepticism by “old school paleontologists” (or by “Eastern Europe school paleontologists”): Instead of considering all kinds of data for phylogenetic hypothesis-making I am supposed to use merely data from the (anatomical, molecular, etc.) comparison of organisms, as if evolution does not manifest in other ways in the geological record.

One could argue that it is possible to integrate other data, i.e. stratigraphic ages and palaeobiogeographical relations, in a cladistic analysis or at least in the discussion of its results, and so assure that hypotheses from the tree perspective on evolution are tested under consideration of independent data.

The idea to use time directly as a character in a parsimony analysis with consecutive time slices as character states may be epistemically unsound, as it is problematic to justify any kind of model assumption how time is weighted with respect to anatomical characters (and implicitly would this mean a post-hoc failure if proximity in time is regarded as indicative for degree of relationship?).

An a posteriori fit to other data – e.g. looking which of the equally parsimonious morphology-only-based time-calibrated trees has shorter lineages of no record (ghost lineages) – might be a better approach, but is still hard to swallow for some people who have problems with parsimony analyses on the basis of (too) small character samples (i.e. with inherent biases due to sample size/ character poorness or ambivalence of fossils).

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.

Questionnaire for Geobloggers(incl. Paleobloggers)

http://geoblogs.stratigraphy.net/survey/

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 geoberg.de, geonetzwerk.org, 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).

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.

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").

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!