mosasaur
laelaps | June 15, 2010
The skull of Mosasaurus hoffmani. From Lingham-Soliar 1995.
On my first trip to the Inversand marl pit in Sewell, New Jersey, I didn't find the wonderfully preserved Dryptosaurus skeleton I had been dreaming of. I picked up a number of Cretaceous bivalve shells and Paleocene sponges, but other than a few scraps of "Chunkosaurus" my excavations didn't yield very much. Before my paleontology class left the site, though, we took a walk by the spoil piles - great green mounds of sediment that had already been mined for glauconite. It had recently rained, and little pillars of the sandy green…
edyong | September 16, 2009
For humans and most other mammals, sex is a question is chromosomes. Two X chromsomes makes us female while an X and a Y makes us male. Birds use a similar but reversed system, where males are ZZ and females are ZW. But for reptiles, including crocodiles, turtles and many lizards, sex is determined not by genes, but by temperature.
In crocodiles, males hatch from eggs incubated at cooler temperatures while warmer conditions produce females. In turtles, it's the other way around, and lizards use a variety of criteria including some very complicated combinations of genes, temperature and…