What Kind of Dinos Did Today's Birds Evolve From?

The hypothesis that today's birds evolved from dinosaurs isn't new, but recent research has filled in clues about exactly how that happened. Learn more in this episode of BrainStuff.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff,
I'm Lauren vogel Bomb, and here's some information you might
already know. Not very much can survive the impact of
a six mile a k a ten kilometer wide asteroid.
Ask the dinosaurs. With that kind of impact, the world

(00:22):
catches on fire, and most terrestrial creatures, by the proverbial
farm within a matter of hours. If the impact and
fire don't kill them, the resulting impact winter blocks out
sunlight for a year or more, making it very hard
for plans to grow and thus for animals to find
food or indeed muster the will to live. So just
how many terrestrial species survived the hellscape that resulted from

(00:45):
an asteroid landing in present day Mexico sixty six million
years ago. Nobody knows, but the dinosaurs were particularly hard hit.
But a report published in a issue of the journal
Current Biology suggests that though the non avian dinos were obliterated,
a handful of small feathered dinosaurs survived, and that these

(01:05):
feathered creatures were the ancestors of modern birds. Of course,
this isn't a new idea that modern birds evolved from
the dinosaurs that survived the last major asteroid ordeal, but
the international team of researchers behind the current report hypothesized
that since forests were burned to the ground all over
the globe and wouldn't return for hundreds or maybe thousands

(01:26):
of years, virtually all the birds alive today descended from
a few small ground dwelling species, probably a bit like
the modern quail that didn't rely on tree habitats. Lead
author Daniel Field of the Milner Center for Evolution at
the University of Bath set in a press release, we
drew on a variety of approaches to stitch this story together.

(01:47):
We concluded that the devastation of forests in the aftermath
of the asteroid impact explains why tree dwelling birds failed
to survive across this extinction event. The ancestors of modern
tree dwelling birds did not move into the trees until
forests had recovered from the extinction causing asteroid The research
team analyzed pollen grains in the plant fossil record to

(02:07):
figure out just how many forests survived the asteroids impact,
and confirmed that the number is pretty close to zero.
Pooling what's currently known about modern bird evolution, they were
able to model a basic bird family tree going back
to the birds that survived this cataclysm. The results of
that analysis suggest that the common ancestors were probably ground dwellers,

(02:28):
and that they survived for years on seeds buried in
the soil. From that small group of birds sprung the
eleven thousand species of birds that Earth supports today. They're
the most diverse group of terrestrial vertebrates that our planet
has going. Now that the researchers have an idea of
where birds come from, their next move is to study
how they radiated out across the globe and to pinpoint

(02:49):
exactly when the forests recovered. Field said, we are working
hard to shed new light on this murky portion of
the fossil record, which promises to tell us a lot
about how birds and other animal groups survived then thrived
following the extinction of t rex and triceratops. Today's episode

(03:10):
was written by Jesselyn Shields and produced by Tyler Clang.
For more on this and lots of other plucky topics,
visit our home planet, how Stuff Works dot com.