Genetics suggests unexpected origins of hummingbirds

Caprimulgiformes is a group of night- and twilight-active (nocturnal–crepuscular), mostly insectivorous birds found on every continent except Antarctica. It includes birds with such colorful names as nightjars, oilbirds, potoos, frogmouths and owlet-nightjars. In addition to their activity times and diet, they tend to have weak legs and some species can even echolocate, using sonar to …

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Genes suggest rhinos, tigers, humans and all other mammals had insect-eating ancestors

Paleontologists have long noted how mammal fossils seem to change dramatically in form from one era to the next. In fact, few things in the fossil record seem to contrast more than the mammals that lived alongside the dinosaurs and those that survived after most dinosaurs went extinct some 66 million years ago. One of the …

Claw gene remnants point to legs in snake ancestors

Nonfunctional remnants of genes (pseudogenes) can often provide evidence of the evolutionary history of life. I once wondered if snakes have any pseudogenes that pointed to a time when they once had legs, a conclusion suggested by comparative genetics and the fossil record. but I had trouble imagining what kinds of genes would provide a …

Genetics of South American rodents points to evolution

Rodents are an extremely successful group of mammals. There are more species of rodents than any other type of mammal, and they inhabit nearly every stretch of land on earth. Some rodents are geographically restricted, however, with a number of groups being located entirely in the Americas. Chinchillas and viscachas (Chinchillidae) are exclusively found in …

Where did the Mesozoic mammals go?

Based on the fossil record and geological dating methods, we think mammals have been around for a long time. So long, that they appear in the fossil record right around the same time as the dinosaurs, and indeed coexisted alongside them throughout the "Age of the Dinosaurs", the Mesozoic era (252–66 million years ago). But …

Turtles, birds and crocodylians have genetic remnants of a ‘third eye’

Many lizards have a so-called 'third eye', more formerly known as a parietal or pineal eye, which is located smack dab in the middle of their heads.   If you dissect a parietal eye, you'll see that it very much resembles a normal eye, with structures similar to a cornea, lens and retina, as well as …

DNA points to reptilian ancestry of birds

As I discussed in the previous post, the fossil record tells a story that at first seems implausible: birds are descendants of dinosaurs. Part of what's surprising about this idea is that dinosaurs typically appeared very reptilian, whereas birds do not. Without providing a formal definition of "reptile", you probably have a general image in your head. This is because reptiles …

Fossils document how dinosaurs gave rise to birds

Everyone knows that dinosaurs are extinct. As children, many of us gazed in awe at the fossils of these magnificent beasts. As adults, a lot of us still do! Except that dinosaurs aren't extinct, at least based on the most recent interpretations of the fossil record and analyses of DNA. The collective evidence points to a conclusion …

Why cats, hyenas and seals don’t love sugar

The molecular basis for taste is relatively straightforward. On your tongue, you have numerous taste buds that harbor cells with little proteins hanging out on the top. These proteins have the capacity to bind a number molecules on your tongue, and thereby transmit information regarding nutritional content. One of these proteins is TAS1R2, which, along …

DNA of wingless insects points to evolution

Perhaps you haven't thought of it much before, but relatively few species of insects completely lack wings. One kind of wingless insect is known as a silverfish, an animal that perhaps you have discovered crawling in your home or hanging out in your pantry. Typical of insects, they possess six legs, a chitinous exoskeleton, compound eyes and a pair …