Smith and co-authors state that Archaeopteryx was the oldest-known feathered dinosaur at approximately 150 million years old, but Anchiornis may have pre-dated its more famous cousin by 10 million years or so. If the new study is correct, parasitic lice proliferated during the Late Cretaceous, when there were already plenty small mammals and feathered dinosaurs running around. The lice appeared to track what was believed to be the early origins of modern groups.īut the tight connection between extant louse families and lineages of modern mammals and birds is an assumption. Since lice are relatively host-specific and are associated with particular groups of birds and mammals, Smith and co-authors used the evolutionary pattern of lice to draw bird and mammal lineages back into the heyday of the dinosaurs. Many paleontologists place the major radiation of modern bird and mammal groups after the end-Cretaceous mass extinction about 65 million years ago, but scientists using genetic and molecular techniques have suggested that these lineages originated deeper in the Cretaceous. This is a subject of some dispute among scientists. Exactly which hosts these insects parasitized is unknown.Įven though news reports about the new study have focused on the likelihood that at least some dinosaurs were bothered by lice, the aim of the research was to use a fresh line of evidence to ascertain the timing of when lineages of modern birds and mammals began to appear. The genetic divergence estimates suggest that parasitic lice were diversifying just after 100 million years ago in a Late Cretaceous world teeming with hosts. What the scientists came up with was a hypothetical tree of louse evolution. Since the prehistoric feather louse and the older "booklouse" remain the only finds close to the early history of lice, the scientists behind the new research used the genetics of living louse species to estimate when their respective lineages would have diverged from one another. This hypothesis is based on comparisons of modern louse lineages. (A 100-million-year-old relative of lice was announced in 2006, but it was a " booklouse" that was not an animal parasite.)Īs yet, no feathered dinosaur specimen has been found with preserved lice, but a Biology Letters study just published by Smith and a different team of collaborators suggests that the pests might have taken up residence on some Cretaceous species. Curiously, though, the single fossil specimen appeared to be a close relative to feather lice found on modern birds, and the researchers who described it suggest that birds may have "inherited from early-feathered theropod dinosaurs." Out of five supposed fossil lice scrutinized by entomologist Robert Dalgleish and colleagues in 2006, only one, a 44-million-year-old specimen described by Dalgleish, Torsten Wappler and Vincent Smith two years earlier, turned out to be the genuine article. The prehistory of lice is poorly understood. Although not as terrible as Aldiss' creatures, prehistoric lice may have made the lives of many dinosaurs very itchy. But not all dinosaur parasites were internal. Tiny trematode and nematode worms lived in the guts of predatory dinosaurs, and Tyrannosaurus itself was plagued by a harmful microorganism commonly found among modern pigeons. Paleontologists have not yet found such monstrous Mesozoic parasites, but familiar pests did afflict dinosaurs. Slaughtering a swamp-dwelling Brontosaurus briefly satisfied his escapist desires, but, unfortunately for Ford, the dinosaur had been home to scores of lobster-sized parasites that scurried off their dead host and onto the closest, warmest living thing. Scores of fictional, time-traveling hunters have learned this lesson the hard way, but arguably the most unfortunate was the protagonist of Brian Aldiss' short story "Poor Little Warrior." All Claude Ford wanted to do was get away from his disappointing life and unhappy marriage by gunning down prehistoric monsters. Hunting dinosaurs is a dangerous business.
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