Author: Science News Staff / Source: Science News
Some scientists are shaking up the dinosaur family tree and raising questions about which features define the ancient reptiles, Carolyn Gramling reported in “New fossils are redefining what makes a dinosaur” (SN: 3/3/18, p. 18).
“I am a bit put out by the continuing references to dinosaurs as being reptiles,” reader David Persuitte wrote. Dinosaurs’ legs were positioned differently than those of modern reptiles, he noted, and many species may have regulated their body temperature, possibly with feathers.
“Dinosaurs should not be referred to anymore as being reptiles,” Persuitte wrote, but should instead be assigned to a new category. “Finally, it is pretty much accepted now that birds are avian dinosaurs. If dinosaurs are reptiles, shouldn’t birds be called avian reptiles?”Persuitte is correct that dinosaurs’ legs were positioned beneath the body, rather than splayed to the side, says Gramling. “But how we define a reptile — or how we define a dinosaur — is closely tied to what sort of classification system we’re using,” she says.
In the original Linnaean system of classification — which focuses on organisms’ characteristics such as temperature self-regulation — birds and reptiles are quite different, of course. In phylogenetics, organisms are grouped by ancestry; a reptile in this system includes any…
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