Biology Now, 2e

The First Bird ■ 261

Tussling with Trees

In January 2013, a year and a half after

Xu published his controversial paper about

Xiaotingia and Archaeopteryx, his work re -

ceived unexpected support. Pascal Godefroit,

a paleontologist at the Royal Belgian Institute

of Natural Sciences, reported the discovery

of a feathered dinosaur called Eosinopteryx

brevipenna. A commercial collector in north-

eastern China had dug up Eosinopteryx in the

same area where Xiaotingia was discovered.

The tiny 161-million-year-old dinosaur was

preserved as a virtually complete skeleton, with

its legs bent and arms out, as if about to jump

(Figure 14.12).

When Godefroit and his team added Eosin-

opteryx to the evolutionary tree of feathered

dinosaurs, they came to the same surprising

conclusion that Xu had: Archaeopteryx was not a

bird. Instead, Archaeopteryx was a raptor along

with Eosinopteryx and Xiaotingia. All three

species share traits that early birds did not have,

such as arms longer than their legs, reduced tail

plumage, and primitive feather development.

Figure 14.11

Cambrian biodiversity

During the Cambrian period, animal diversity

increased dramatically. The remains of many of

these species have been found in Canada (the

Burgess Shale), China (the Maotianshan Shale),

and fossil beds in Greenland and Sweden. Some of

the fossils look familiar, resembling sponges and

brachiopods, but do not appear to be related to

any living groups of animals.

Cambrian explosion

4,600 545 490 445

mya

Precambrian Cambrian Ordovician

But science is a continuously changing

process, and only 4 months later, Godefroit

published data about another birdlike fossil

that caused him to revise his hypothesis once

again. This time it was a feathered dinosaur that

Godefroit found collecting dust in the archives

of a Chinese museum. The 18-inch-long fossil

had small, sharp teeth and long forelimbs.

Godefroit believed the dinosaur, which his team

named Aurornis xui to honor Xu’s work, proba-

bly couldn’t fly, but instead used its wings to glide

from tree to tree. But its other features, includ-

ing the hip bones, were clearly shared by modern

birds (Figure 14.13).

Using Aurornis, Godefroit constructed

another evolutionary tree. This time he started

from scratch, compiling data on almost a

Pascal Godefroit is a paleontologist at the

Royal Belgian Institute of Natural Sciences

in Brussels. He has discovered numerous

feathered dinosaurs.

PASCAL GODEFROIT