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Sabrina Hamilton
Mr. Jordan
EH 101
November 5, 2016
Word Count: 1,497
Birds are Really Dinosaurs
Birds are everywhere. Look outside and you’ll hear them chirping and see them flying or
perching in trees. These wonderful creatures come in many different varieties. Some are bright
and colorful while others are plain, dark colors. There are even some birds that can learn to say
words. Birds have different ways of living, surviving, and even eating. There are over 10,000
species of birds (Bhullar et al. 223). They are also very diverse. A good example of this diversity
would be how ostriches are very big, non-flying birds while hummingbirds are tiny and have
such fast moving wings that it is hard to see them. We see birds every day of our lives going
about their business but we never stop to think about what birds have descended from. Since
birds all look very unique and different based on the type of bird being observed, it seems like
they came from their very own group of animals. It’s easy to overlook how birds have scales on
their legs and reptile-like eyes. These features are what make scientists wonder if birds are
actually related to dinosaurs. Paleontologists and biologists and have studied birds for many
years and have found evidence to prove that birds are related to a very old and unexpected group
of animals. Based on my research, I believe that birds are dinosaurs because of scientific studies
that show the many similarities between them.
A recent study on birds and saurischian dinosaurs (land-dwelling, bipedal, carnivorous
dinosaurs) showed that bone cells in modern birds have a large surface area and cytoplasmic
surface area like saurischian dinosaurs did. This showed the similarity between modern birds and
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dinosaurs which supports the claim that birds are actually dinosaurs. John Rensberger and
Ricardo Martinez conducted a study on the surface area and density of osteocytes (bone cells) in
both modern-day birds and saurischian dinosaurs by collecting fossil samples from different
museums and skeletons of modern road-kill (Rensberger and Martinez 4). The “osteocyte
lacunae and canaliculi”, which are bone cavities that contain the bone cells called osteocytes,
were used in their experiment (Rensberger and Martinez). Rensberger and Martinez cut cortical
bone, which is the compact, structural bones in vertebrates, small enough for the individual bone
cells to be seen and measured under a microscope. They took digital pictures of each magnified
sample to be measured and compared. Samples that had no scratches, cracks, or imperfections
were used in order to insure accuracy in the experiment (Rensberger and Martinez 4). According
to Rensberger and Martinez, “For each sample, the sum of the lacunar perimeters was added
twice the total canalicular length (the latter approximating the canalicular perimeter) to provide a
correlate of the cytoplasmic surface area in the sample (5).” This is the method they used to take
accurate measurements. What Rensberger and Martinez found was that saurischian dinosaurs’
osteocytes had a greater surface area and canalicular density than non-saurischian dinosaurs
which was also found in modern birds (6). This experiment showed how birds have some of the
same characteristics as saurischian dinosaurs, proving how they descended from the ancient
beasts.
Another study on how birds have evolved and descended from dinosaurs had to do with
skull structure. Photos and CT scans of bird embryos were compared to dinosaurs and showed
many distinct similarities. An important one was how both bird and dinosaur skulls are
“paedomorphic”, which means that as they grow and develop from embryos to adults, they have
major similarities (Bhullar et al. 224). According to Bhullar and his associates, “The cluster of
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adult early bird relatives with the youngest individuals of more basal archosaurs supports the
hypothesis of paedomorphosis,” the hypothesis being that birds and dinosaurs have similar skull
structure (Bhullar et al. 225). As both birds and saurischian dinosaurs aged, their faces extended
and the “lower temporal fenestra”, holes in the side of the skull, tightened and shrunk (Bhullar et
al. 224).
That was not the only study that was done of the development of birds and dinosaurs
however. According to John Pickrell, science writer of archeology and paleontology for
Australian Geographic, there is even more evidence that bird development is similar to dinosaur
development. Pickrell states that “the prevailing wisdom was that dinosaurs grew in a similar
way to living reptiles, such as crocodiles, which slowly increase in size throughout their lives,
only attaining their greatest size in old age. But many studies of fossil dinosaur bones now hint
that they, in a similar way to birds, underwent much more rapid bursts of growth in early life to
reach a large size respectively swiftly (51).” Because of the fossil evidence that dinosaurs grow
as quickly as birds as opposed to reptiles (what most people thought birds have evolved from),
scientists were able to help prove how birds have evolved from dinosaurs. The fact that birds
formed and developed the same way as theropods and saurischian dinosaurs is good evidence
that birds really did evolve from dinosaurs. It also shows how birds still have some of the same
characteristics as their ancient relatives.
A very important characteristic of birds is their feathers. It’s debated by many scientists
when and why feathers actually developed. Li and his associates have studied “melanosome”,
organelles that reflect light and bring out colors in animals, in ancient birds and their close
relatives (350). They found that dinosaurs that were closely related to extant or, still-living birds
had the same amount of color diversity (Li et al. 352). There has been debate in the scientific
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community whether or not dinosaurs even had feathers. According to John Pickrell, a small
dinosaur was discovered by a farmer named Li Yinfang from northeastern China (17). John
Pickrell states that “the animal had a relatively large skull, similar in shape to a bird’s, a very
long tail, and what appeared to be fuzzy fringe of dark feather-like structures along its head, back
and tail (18).” Lots of scientists didn’t believe that the fossil was real or that the feathers were
actually feathers (Pickrell 18, 19, 20, 21). Some said that the feather-like markings could’ve just
been stains and minerals in the stone in which the fossil was imprinted (Pickrell 18). Many
doubtful paleontologists were actually able to see it in person and were convinced that it was real
and that the feather-like markings really were feathers. Pickrell stated that “This little fossil
caused a sensation around the world and shook the paleontological community to its very core
(21).” The fossil came as a shock to many paleontologists. After studying this amazing
discovery, paleontologists had confirmed that birds are in fact dinosaurs.
Despite all of the evidence that birds are dinosaurs, some people still disagree. According
to R. Monastersky, writer for Science News, there is strong evidence that birds are not related to
dinosaurs. He talks about John Ruben, “a physiologist at Oregon State University in Corvallis,” and
how he “compared the lungs of living birds and crocodiles with evidence from dinosaur fossils”
(Monastersky 1). Monastersky says that “crocodiles, like mammals, draw air into their lungs
with the help of a diaphragm, a movable tissue that divides the chest cavity from the abdomen”
but “birds have a different lung system, one that doesn’t rely on a diaphragm to alter the pressure
in the chest cavity”(Monastersky 1). They determined that dinosaurs were more like crocodiles
than birds, but this is only a small amount of evidence. Even though this study makes sense,
there is more proof that birds are dinosaurs. According to John Pickrell, a dinosaur fossil was
found in the sleeping position that a lot of modern-day birds sleep in and “gas from a volcanic
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eruption suffocates her . . . leaving her frozen in this sleeping posture” (47). Scientists were able
to link the behavior of the ancient dinosaur embedded in the fossil with birds, which further
proves that birds are dinosaurs.
In conclusion, I believe that birds are dinosaurs because of the clear evidence that modern
scientists have provided us. The discovery of ancient fossils with bird-like features that led
paleontologists to rethink where birds actually came from is the reason why there is so much
evidence that birds are really dinosaurs. They go through similar changes in development, have
similar skull structures, and there’s even been a fossil found containing feather markings in the
stone. Even though the lung structure of dinosaurs is similar to crocodiles, there are still many
studies that prove birds are dinosaurs. Birds are often overlooked by many people, but for
scientists, they are our only connection to dinosaurs. Since they have so many of the same
characteristics as dinosaurs, it makes sense that they are their close relatives. Scientists have
noticed how birds have scales on their legs, talons, and dinosaur-like eyes and that really made
them wonder if there was a connection between dinosaurs and birds. How cool is it to think that
the birds you see every day have descended from the ancient and intriguing dinosaurs of Earth’s
past?
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Works Cited
Bhullar, Bhart-Anjan S., et al. “Birds have Paedomorphic Dinosaur Skulls.” Nature, vol. 487, no.
7406, July 2012, pp. 1, 223-226.
Li, Quanguo, et al. “Melanosome Evolution Indicates a Key Physiological Shift Within
Feathered Dinosaurs.” Nature, vol. 507, no. 7429, March 2014, pp. 350-353,
doi:10.1038/nature12973.
Pickrell, John. “Flying Dinosayrs: How Fearsome Reptiles Became Birds.” Columbia University
Press, 2014. eBook Academic Collection (EBSCOhost). November 2016, pp. 17-21,47,
51.
Rensberger, John M., and Ricardo N. Martinez. “Bone Cells in Birds Show Exceptional
Surface Area, a Characteristic Tracing Back to Saurischian Dinosaurs of the Late
Triassic.” Plos One, vol. 10, April 2015, pp. 4-6, Public Library of Science.
Monasterky, R. “Biologists Peck at Bird-Dinosaur Link.” Science News, vol. 152, no. 20,
November 1997, pp. 1.