It’s commonly stated that modern birds are living dinosaurs and penguins are birds. So it would seem so. But based on recent penguin “missing link” find articles, they claim that penguins evolved after the dinosaurs were ‘wiped out’.
I realize that journalist aren’t scientist but still it made me wonder.
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It’s just a journalist speaking imprecisely. By “dinosaurs” he means the popular conception of dinosaur (a big lizardy thing). But any taxonomic grouping that includes what people think of as dinosaurs also includes all birds, including dinosaurs. The fact that modern penguins evolved after the creatures that showed up in Jurassic Park were extinct doesn’t matter.
All extant bird species evolved after the (other) dinosaurs were wiped out, nothing special about penguins.
“Dinosaur” is a huge family of species, grouped into smaller groups of species.
It was a huge living family before one of the Earth’s bigger extinction events.
“Birds” is one of the branches of that family. They are a specific group of Theropods, which are a specific group of Dinosaurs. It’s a sub-branch of a sub-branch of a bigger tree, which is, itself, a sub-branch of the massive tree of all life on Earth, past and present. You can distinguish birds from non-bird dinosaurs, but there’s no way to say birds aren’t dinosaurs, any more than you can say housecats aren’t mammals.
You can look at this nested list to see how everything’s situated. Search for “Aves” to see where all birds, past and present, are attached to the tree. Every group name with a cross in front of it is completely extinct.
Nitpick: That’s true if by “taxonomic grouping” you mean “monophyletic taxonomic grouping,” but in fact paraphyletic groupings are in widespread use.
If only monophyletic groupings are allowed, then insects are crustaceans, butterflies are moths, snakes are lizards, ants are wasps, whales are even-toed ungulates, trees are algae, humans are fish, all mammals are sponges, and … all living creatures are bacteria!
All they mean by that is that the birds we recognize as penguins developed after the KT extinction event. It’s a pretty stupid headline, since pretty much every kind of bird we recognize today evolved after the non-bird dinosaurs went extinct.
Many kinds of birds existed before the KT event, including both the lineages that led to modern birds as well as others now extinct. Actually, the most common birds before the event were those known as Enantiornithes (or “opposite birds,” because their ankle joints were formed in an opposite way from modern birds) but all of these were wiped out.
The KT event appears to have wiped out all tree-living birds, and only four to six lineages of ground dwelling birds survived, including the ratites (ostriches etc), waterfowl, chicken-like birds, and the ancestor of all other birds. These lineages, especially the last, underwent very rapid divergence immediately after the extinction event, and most modern groups originated in the Paleocene/Eocene.
The article actually says that the ancestors of penguins split from their nearest relatives, the albatrosses and petrels, before the KT event, so it’s not even accurate to say that penguins originated after non-avian dinosaurs became extinct. It’s just that the lineage that led to modern penguins split from older kinds of penguins after the extinction event
Thanks guys. And thanks for the links.
I see what you are saying Colibri. I guess I didn’t stop to think that all birds today evolved after dinosaurs went extinct.
Still it seems weird to think of penguins as dinosaurs.
I dunno. Penguins seem pretty dinosaurish to me, compared to things like finches and hummingbirds.
I think geese might be the winners in the “looks like a dinosaur” contest.
I find this illustration very helpful to “unweird” it some.
I don’t think many people realize how much like birds certain non-avian dinosaurs like Anchiornis looked. And no, that’s not a bird, but from a different lineage than that that led to modern birds. Some, like the bizarre four-winged Microraptor, may have been capable of powered flight. Many small feathered theropods looked much more like typical birds than penguins do.
Since the OP has been answered, I hope it’s ok to ask a followup.
Why did the Enantiornithes go extinct while the ancestors of modern birds did not? Just reading the Wiki on them, they were highly diverse and widespread, with all sorts of special adaptations, and they too had the power of flight. They seem like the sort of animal that would have had at least some survivors.
Were they just out-competed by what would become modern birds, or was there something about their flight capabilities or growth rate (both mentioned in the Wiki article) that made them inefficient in the post-KT world?
I always enjoy watching the roadrunners around here; it’s very easy to think of them as little dinosaurs (especially when they’re hunting lizards). This one looks a lot like your Anchiornis. And this one resembles the microraptor.
I don’t think that anything other than the luck of the draw is necessary to explain their extinction. As I mentioned as few as four to six lineages - possibly as few as six species, but probably more - of modern birds survived the KT event. There’s no evidence that any Enantiornithes survived the event and were outcompeted subsequently.
As I said, all tree-dwelling birds apparently went extinct. The surviving modern bird lineages were ground birds at the time. It also appears they may have also been seed-eaters. Enantiornithes mostly still had teeth rather than beaks like modern birds, so perhaps lacked specialized seed-eaters.
I don’t think that anything other than the luck of the draw is necessary to explain their extinction. As I mentioned as few as four to six lineages - possibly as few as six species, but probably more - of modern birds survived the KT event. There’s no evidence that any Enantiornithes survived the event and were outcompeted subsequently.
As I said, all tree-dwelling birds apparently went extinct. The surviving modern bird lineages were ground birds at the time. It also appears they may have also been seed-eaters. Enantiornithes mostly still had teeth rather than beaks like modern birds, so perhaps lacked specialized seed-eaters.
That really puts things into perspective. It was hell on earth, and we’re kind of lucky that any higher animals survived.
Makes sense. Seeds can last for a long time, even surviving fire and floods, so seed-eaters had a path to survival. Thanks!
Behold the terror that is the Common Merganser!
ETA: The first time I saw one walking on land( something they don’t do a lot of ), I thought it looked distinctly raptorial, with a triangular crested head, toothy mouth and the way the feet are set father back in the body giving it a kind of lurching, menacing gait.
Yikes! That and **Machine Elf’**s goose photo are downright scary. I’ve seen common (and hooded) mergansers here in New Mexico, but not walking on land. We get quite a variety of water birds here, mostly along the Rio Grande. I saw a flock of white pelicans in October, just south of Elephant Butte. Bosque Del Apache Wildlife Refuge (which is north of Elephant Butte) gets a huge variety of birds migrating through.
That’s not quite true. “Butterflies” are a monophyletic group, so are “humans” - “Whales” are a polyphyletic group, though.
You misunderstand. All of the first-mentioned groups (except trees, and they are being used as a stand-in for multicellular green plants) are monophyletic. But if they are removed, the second group becomes paraphyletic. For the second groups to be monophyletic, the first groups must be considered to be part of them. (And “whales” is being used in the broad sense, to include dolphins and other toothed whales. In that sense all cetaceans are monophyletic.)
