Fossilized snake with exploded head

There is a temporary exhibit called “Geopalooza! A Hard Rock Anthology” at the Houston Museum of Natural Science. If you are in Houston this summer (until August 24), this is something absolutely worth checking out: you can see some outstanding geodes, crystals, meteorites, and fossil specimens. I have been to many natural history museums, but I rarely get as high as I did at the HMNS the other day [‘getting high’ is the right terminology here: you get to (or have to) listen to Led Zeppelin and Bob Dylan while looking at the rocks]. Even if you are not too much into rocks, minerals, fossils, and natural science in general, these pieces are so beautiful that they can simply be viewed as works of art.

Here is for example a fossil snake from the Eocene Green River Formation in Wyoming. This formation has not only one of the most significant fossil sites in the US, but it also contains the largest oil shale deposit in the country: there are 1.5 trillion barrels of shale oil within the former lake sediments. Preservation of both fossils and of organic matter requires special conditions on the lake bottom: a partial or total lack of oxygen not only prevents oxidation of organic material, but also makes life difficult for critters that otherwise would totally churn the sediment and leave no undisturbed animal remains behind.

One of the museum curators was around when I was checking out this snake and she explained that the reason why the head bones are in such a disarray – compared to the beautifully arranged backbone and ribs – is that, as the snake’s body started to decompose, the easiest way out for the accumulating gases was through the head.

I think this snake must belong to the species Boavus idelmani, and is probably one of the best preserved fossil snakes in North America.

The rest of the photos from Geopalooza are here.

Crop circles of the deep sea

If ‘cereologists’ (people who seriously think that crop circles are made by aliens) knew about deep-water trace fossils, I am sure at least some of them would argue that these structures must also be the work of extraterrestrial intelligence. Many of the traces are so intricately constructed that they raise the question: how is it possible for a not-too-brainy animal to create such patterns.

This group of trace fossils is called ‘graphoglyptids’ (don’t ask me why) and they are usually found on the soles of turbidite sandstones, layers of sand deposited in the deep sea (that is, in water depths of more or much more than a few hundred meters). Their shapes can be relatively simple meanders, can include multiple levels of meandering, meanders with bifurcations, spirals, radial patterns. The most interesting and most famous member of the group is Paleodictyon, an easy-to-recognize trace fossil with almost perfect honeycomb-like hexagonal patterns.

Many years ago I was lucky to do some work on trace fossils of the Carpathian flysch with two of the best trace fossil experts; since then I haven’t worked with trace fossils but now I wish we did more documentation of the trace-fossil-rich outcrops in the Romanian Carpathians. The Paleodictyon pictures below show turbidite sandstone soles from the Buzău Valley; I haven’t been there for a while but I hear that many of the outcrops are covered now.

The first weird thing about graphoglyptids is that they developed high diversity in an environment with limited amounts of low-quality food (lack of sunlight, hence no primary production; and stuff that sinks down from the photic zone usually has already been food for some other animal). The second weird thing is that they are not simple grazing traces like the tightly meandering patterns of sea urchins; the most widely accepted idea is that they are farming traces. In other words, these guys (whatever they might be, nobody really knows) create well aerated open burrow systems a few millimeters below the sea floor, with multiple openings to the sediment surface, so that chemosynthetic bacteria move in to get the necessary oxygen to oxidize methane and hydrogen sulphide, their favorite food.

Again, despite the abundance of these traces in turbidite successions, it is not clear what is the animal that likes to build delicate hexagonal burrows in the deep sea. It is clear however that the exact same structures have been found near the Mid-Atlantic Ridge. In 1976, Peter Rona of Rutgers University and his colleagues were looking at photos of the Atlantic seafloor and discovered some interesting geometric patterns of black dots. When Adolf Seilacher of the University of Tübingen, probably the most famous trace fossil expert, saw the pictures, he got very excited: he became convinced that it was a modern Paleodictyon. Unfortunately, no other data than the photographs with the black dots was available; no animals recovered from the sediment, and no hexagonal patterns seen below the surface. It took more than 26 years before Rona and Seilacher had the opportunity to do a new dive with the submersible Alvin and to show that the black dots on the seafloor indeed represent small shafts that belong to a hexagonal pattern a few millimeters below, a pattern identical to Paleodictyon (more details in an article by Peter Rona in Natural History Magazine; picture below is from the same article and is © of The Stephen Low Company).

This story is fascinating as it is, but it is best to see it in amazing colors and resolution, in the IMAX movie “Volcanoes of the Deep Sea“, a documentary about the black smokers of the Atlantic and the discovery of modern Paleodictyon.

The mystery of the tracemaker of Paleodictyon – and all other graphoglyptids – remains unsolved: despite the outstanding success of taking IMAX-quality pictures at the bottom and the middle of the Atlantic Ocean, no animal was ever found in the sediment samples, and we know much more about how actual crop circles are generated than we do about the behavior of Paleodictyon.

Further reading

A beautifully illustrated new book by Adolf Seilacher:
Seilacher, A. (2007) Trace Fossil Analysis. Springer, 226 p.

Paper on trace fossils in the Carpathian flysch:
Buatois, L.A., Mangano, M.G. and Sylvester, Z. (2001) A diverse deep-marine ichnofauna from the Eocene Tarcau Sandstone of the Eastern Carpathians, Romania. Ichnos, 8, 23–62.

Links to this post: Book of Barely Imagined Beings

Kingdoms of Either and Or

Something really worth taking note of, from Jonathan Weiner’s The Beak of the Finch (p. 231-232):

Currently most evolutionists regard the possibility of speciation among neighbors as unorthodox, even though Darwin himself proposed it. The standard model of speciation requires geographic isolation. That has been the canonical pattern for half a century, and many evolutionists belive it is the universal pattern. But evolutionists are forever dividing and subdividing into schismatic sects, kingdoms of Either and Or. Do new species arise in archipelagoes, like Darwin’s finches, or do they arise among neighbors? Is the origin of species fast or slow? Is the mechanism natural selection or sexual selection? And so on. None of these questions really have ot be framed either-or. It is almost a law of science: the more indirect the evidence, the more polarized the debate. Evolutionists sometimes catch themselves sounding like the Little-Endians and Big-Endians in Gulliver’s Travels, fighting tooth and nail over the proper way to crack an egg. Meanwhile, the more direct the evidence, the less the answers look either-or.

This ‘law’ of indirect – or poor – evidence resulting in more polarized debates seems to work in other areas of science as well. For example, in sedimentary geology, there is (was?) a strong debate about whether most thick-bedded sands deposited in the deep sea are due to deposition from turbidity currents or debris flows. Probably the only positive outcome of the debate is that some people are paying more attention to the evidence and they are starting to realize exactly that “the more direct the evidence, the less the answers look either-or”. Debris flows can easily become turbulent flows – and the other way around: in their final, depositional stages, turbidity currents can transform into predominantly laminar flows. To claim that 99% of deep-water sands result from debris flows rather than turbidity currents just because many depositional features suggest laminar behaviour is a perfect example of thinking in terms of black-and-white or kingdoms of ‘Either and Or’. It is analogous to calling cars ‘frictional machines’ because they use friction to stop.

Understanding evolution

I stumbled upon a new website on evolution, created as a teaching resource by the by the University of California Museum of Paleontology. Among its many authors are Eugenie C. Scott (director of the National Center for Science Education) and Carl Zimmer (who wrote Evolution: The Triumph of an Idea). Excellent website, there is material that could fill a book (or more), including subjects like the nature of science, evolution 101, history of evolutionary thought, etc. It is websites like these that increase exponentially the value of the internet and make it worthwile to pay the monthly fee for a high-speed connection…

First post on this blog, on a rainy Saturday. (It tends to rain on weekends over here).

Bought a few days ago the new issue of Skeptic. It has a chapter in it from the new book by Simon Conway Morris (Life’s Solution : Inevitable Humans in a Lonely Universe). Quite disappointing: “…at some point and somehow, given that evolution has produced a sentient species with a sense of purpose, it is reasonable to take the claims of theology seriously”. Or: “In essence, we can ask ourselves what salient facts of evolution are congruent with a Creation.”

Luckily, a good review follows by Donald Prothero that summarizes the issue very well: “Well written trade science books are a vanishing breed, marketed to smaller and smaller audiences who are easily suckered into reading and believing pseudoscientific babble and religious tracts masquerading as science. What a pity that such a distinguished scientist as Conway Morris (who has produced much excellent science in the past) falls into the latter trap with this book.”