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News in Brief

Titanoboa!


Titanoboa compared with Anaconda vertebra (left)Regional mapping in the Rift Valleys, which occupied me for a decade, was rather like the Garden of Eden, inclusive of snakes. I had a nasty encounter with a seven foot mamba, which struck out head-high and also a miss by inches from a saw-scaled viper. However, the new report by Jason Head (University of Toronto at Mississauga) and others (Nature 5.2.2009) is about something different.

Vertebrate fossils are very rare in the Paleocene rocks, of the 10 myr after the K/T extinction, and palaeontologists from the University of Florida, led by Jonathan Bloch, have been studying samples from the huge Cerrejon opencast coal mine in NE Colombia, in rocks 60-58 Myr old. They were surprised to discover fossil vertebrae of enormous dimensions, of a constrictor snake up to 13m long (the maximum length of an Anaconda is 5.5m). It weighed 1135kg. They recognised 28 giant snake individuals among the fossils. Associated were turtle, crocodile and fish fossils, and it is suggested that the snake fed on crocodiles and turtles. The snake has been named Titanoboa cerrejonensis. Its length equals that of Tyrranosaurus, which however had become extinct by the time of the K/T event, so they never met.

This discovery poses important questions about climate: the cold-blooded snake lived mostly in water, but also slithered on land through the rainforest. It is calculated that for it to thrive an average temperature of 30-34°C would be required, 3-4 degrees warmer than today in coastal Colombia. There has been argument whether equatorial regions get hotter under natural global warming, and this discovery suggests that they do.


Sponges from Oman Cryogenian rocks yield fossil steroids


Love et al. report the presence, in the Huqf Supergroup of the South Oman Salt Basin, of isopropylcholestanes, the hydrocarbon remains of C30 sterols produced by marine demosponges. The Neoproterozoic (1000-542Ma) was an era of climatic extremes and biological evolution culminating in the emergence of animals. These sedimentary rocks were deposited prior to the end of the Marinoan glaciation, ~635Ma. There is a record thus of demosponges from this time through the terminal Neoproterozoic into the early Cambrian. This is the oldest evidence of animals in the fossil record. The shallow shelf seas prior to the glaciation apparently contained enough dissolved oxygen to support Metazoan life. There is no evidence yet of ancient sponges predating the first Neoproterozoic glaciation (Sturtian, ~713Ma) in Oman.

Ref: Love, G D, Grosjean, E., Stalvies, C et al. 2009. Fossil steroids record the appearance of Demospongiae during te Cryogenian period. Nature 457; 718-721.


First andesitic meteorite


A most important contribution to meteoritic research comes from Day et al.1 Basaltic meteorites (e.g eucrites, howardites) provide evidence that, like terrestrial planets, some asteroids generated crust, undergoing large-scale differentiation processes. Until now, no felsic asteroidal crust has been represented among the many described meteorite types. However, the paired, differentiated Antarctic-sourced Graves Nunatak (GRA) 06128 & 06129 are feldspar-rich, with andesitic bulk composition. These have an age of formation close to the formation of the solar system – 4.52 (plus or minus 0.06) Gyr. They are believed to emanate from partial melts in a volatile-rich, oxidised asteroidal parent body. This implies a quite new style of crust formation and a previously unknown diversity in the early formed materials of the solar system. The authors publish plots of δO18 and ΔO17, also of Re-Os isotope systematics: from these it is clear that these meteorites are closest to the brachinites, lodranites and acupulcoites, rare meteorites that “draw a blurred line between achondrites (differentiated meteorites ) and chondrites. They are all igneous or metamorphic rocks, but hold a tantalising record of their chondritic pedigree2. They even, in rare cases, preserve isolated chondrules, and these seem to represent incomplete obliteration in the metamorphic process. Such meteorites can be considered as extreme cases of the metamorphic processes which progressively affected some chondritic meteorites. The polymict ureilites, also differentiated meteorites, contain chondrules, but these are typically in contained clasts, and are mainly of the rare Rumuruti (R) chondrites, and it is believed that an R-chondrite asteroidal body and some other chondrite bits collided in Space long ago with the ureilite parent body.
  1. Day, J M D , Ash, R D , Yang Liu, Belucci, J J , Rumble, D III , Mc Donough, W F , Walker,R J , Taylor, L A 2003: Early formation of evolved asteroidal crust Nature 457(8); 179-182
  2. Bevan, A , de Laeter, J R 2007: Meteorites: a journey through space and time Smithsonian Institute Press, Washington, London; 215 pp