Are penguins considered dinosaurs

[Andy_L]

@Colibri

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.)

Got it. My apologies.

[DesertDog]

@Colibri

Many small feathered theropods looked much more like typical birds than penguins do.

The Arizona Museum of Natural History where I volunteer is real proud of its Suskityrannus hazelae specimen. The articulated skeleton is in the Dino Hall on the main level and last May, a life-size model was placed at the base of the Dinosaur Mountain exhibit. Both are of a juvenile and the model is covered with “filimentous feathers” (the model maker confessed he faked them with fur). The current thinking is that a lot of young dinos were feathered for conserving body heat, but lose them as they mature.

@GreysonCarlisle

That really puts things into perspective. It was hell on earth, and we’re kind of lucky that any higher animals survived.

IIRC no land specie over ten kilos survived the K-T event.

[Really_Not_All_That_Bright]

@Colibri

Many kinds of birds existed before the KT event…

I did not know this. Thanks!

[Colibri]

@Colibri

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.

I should clarify that the base of the split within the maniraptors between the lineage that led to modern birds and that that led to dromeosaurs/troodontids is very fuzzy and rather arbitrary. Every new analysis seems to shift some species from one side of the line to the other. In the link for Anchiornis above, it is shown as being an early split from the combined lineage of birds/dromaeosaurs/troodontids, while in the article on Avialae, basically the bird lineage, it is shown as being a member of that group. Note that Avialae itself is pretty much a group defined for convenience by including Archaeopteryx as the first known “bird.” Some studies have concluded that Archaeopteryx is more closely related to dromaeosaurs/troodontids than modern birds.

Regardless, there are still some feathered, apparently flying dinosaurs like Microraptor that were outside the bird clade.

[Sailboat]

@Colibri

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.

A lot of people underestimate the potential impact of contingency (“the luck of the draw”) on evolution. It turns out “shit happens” is a valid evolutionary principle that helped shape biology as we know it.

[Skywatcher]

Penguins are now Snow Chickens.

[Chronos]

Quoth septimus:

and … all living creatures are bacteria!

Nitpick: Eukaryotes are not descended from bacteria. Eukaryotes and bacteria are both descended from archae. And in fact, there are some modern archae that are more closely related to us than either are to any bacteria.

[Colibri]

@Chronos

Nitpick: Eukaryotes are not descended from bacteria. Eukaryotes and bacteria are both descended from archae. And in fact, there are some modern archae that are more closely related to us than either are to any bacteria.

Actually, Eucaryotes and Archaea are both descended from a common ancestor that was descended from Bacteria (or a bacteria-like organism). The fact that they are more closely related to one another than to Bacteria indicates that Bacteria is the basal group.

Now it’s arguable whether the common ancestor to Bacteria on one hand, and Archaea/Eucaryota on the other, should be called a Bacterium. But if it is, then all living things would fall within a monophyletic Bacteria.