Geoscience Reports 28:5-6 (Fall 1999).

NOTES FROM THE SCIENTIFIC LITERATURE

Paleontology

Erickson G. 1999. Breathing life into Tyrannosaurus rex. Scientific American 281 (3 Sept):42-49.

    Researchers now have 22 nearly complete specimens of T-rex and at least two quarries are currently being excavated. T-rex bite marks on the bones of Triceratops and Edmontosaurus (a duck-billed dinosaur) suggest both predatory and scavenging behavior. Twice as many bite marks are found on the duckbill as on the ceratops. Bite marks are also found on the skulls of other tyrannosaurs, particularly juveniles. Gouges and punctures are found predominantly along the sides of the snout and jaws. Though many disarticulated skeletons have been found, a lack of long bone, T-rex bite marks indicate that juveniles were apparently not cannibalized.
    Comment: The paper included a report on T-rex coprolites (fossil feces); however, from the information given, it was not clear why the author had concluded the specimen was a coprolite, much less a T-rex coprolite.

Ruben J, Dal Sasso C, Geist N, Hillenius W, Jones T, Signore M. 1999. Pulmonary function and metabolic physiology of theropod dinosaurs. Science 283(Jan):514-516

    Researchers analyzed an articulated skeleton of a theropod dinosaur (Scipionyx) under ultraviolet light and discovered partial preservation of several internal organs: intestines, liver, trachea and skeletal muscles. The position of the colon in the dinosaur is similar to that of crocodiles and mammals, not birds. This position suggests that the dinosaur did not have abdominal air sacs, such as modern birds have. The location of the liver is the same as that of the crocodiles and effectively divides the chest from the abdomen. Researchers also believe they have evidence of diaphragm muscles. This dinosaur is the second genus to be reported with a diaphragm so the authors conclude that diaphragms were probably common in dinosaurs. The soft tissues preserved in this dinosaur and the lack of respiratory turbinates in the nasal cavities prompted the scientists to postulate the metabolic physiology of Scipionyx as similar to that of reptiles; however, they also believe the dinosaurs were capable of sudden and sustainable bursts of activity beyond that possible by reptiles today.
    Comment: Evidence continues to mount against the dino-bird link that the media promotes. Not only do we have skeletal features (pelvic and digit structures), but now we have soft tissues that are inconsistent with the proposed bird link.

Geology

Pope K, Ocampo A, Fischer A, Alvarez W, Fouke B, Webster C, Vega F, Smit J, Fritsche A, Claeys P. 1999. Chicxulub impact ejecta from Albion Island, Belize. Earth and Planetary Science Letters 170:351-364.

    The authors suggest that ejecta deposited considerable distance from the impact is significantly affected by the atmosphere. The distal ejecta consists of fine-grained material (mostly smectite) deposited by turbulent debris clouds, as well as atmospherically sorted clasts. Geochemical analyses indicate that the smectites from this area have a high Si/Al ratio similar to other K/T boundary clays.
    Comment: One of the authors of this paper on the Chicxulub ejecta is Dr. Clyde Webster, our geochemist at GRI.

Kirkland B, Lynch F, Rahnis M, Folk R., Molineux I, McLean R. 1999. Alternative origins for nannobacteria-like objects in calcite. Geology 27(4):347-350.

    Laboratory experiments regarding calcite precipitation indicate that round, nannobacteria-like structure, can be formed inorganically. Acid etching also produced nannometer-scale structure. The greatest abundance of these features were produced in calcite associated with dissolved organic material and this is consistent with observations of the high relative abundance of nannobacteria-like features in minerals formed in organic-rich environments as opposed to environments with lower organic content.
    Comment: The database for claims of primitive bacteria in ancient rock needs to be carefully assessed. Inorganic origin and modern contamination are two possibilities that need to be considered and clearly ruled out by the data before the claims regarding microfossil occurrence can be accepted.