There never was much doubt that
large land based birds existed since we came across isolated pockets of them in
historical times. The difficulty was
that they could not survive contact with land carnivores in general and
certainly not with humanity. Survival
during the dinosaur age had to be just as difficult and probably meant finding
refugia for nesting.
Large flying birds had a far
better survival prospect so it appears creditable that some of theses large
birds did fly.
Again we do have legends. Yet populations would have always been scant
and once humanity had both spears and arrows, they had the means to kill such
predators. Recall also the Western
Indian tradition of young men collecting an eagle in order to get the feathers
for ceremonial purposes. Any daytime
giant bird would be soon hunted down.
We have speculated in this blog
that certain sightings are giant owls that are naturally nocturnal and have a
natural prey supply in the form of rabbits.
Been nocturnal, they would have readily avoided human attentions.
What we now know is that the
natural world left to its own devices will produce a wide range of large birds
able to take advantage of obvious niches and that it surely did. Those same birds were simply far too vulnerable
to human hunters in the same way that the cave bear was vulnerable. It is simply way too easy to run them to
ground.
Gigantic Birds Walked the Earth During Dinosaur Age
Published August 10, 2011
John Conway
Scientists aren't sure if the ancient bird flew or was grounded (both
body shapes shown here), but either way it was enormous, much larger than
"normal size" Mesozoic birds (shown in background) and larger than
humans.
An enormous bird, taller than an adult human, walked the Earth (and
maybe flew above it) more than 80 million years ago, according a newly
discovered fossilized jaw. The finding suggests oversize birds were more common
during the Age of Dinosaurs than scientists thought.
Scientists have long known that birds, or avian dinosaurs, lived during
the Mesozoic, the era when dinosaurs ruled the Earth. Although researchers have
discovered numerous Mesozoic bird species, these were virtually all the size of
crows or smaller.
Partial lower jaws of the giant Cretaceous bird Samrukia: Posterior
region from above (a) and below (b), jaw's right side, seen from the outside
(d) and the inside. CREDIT: Naish, Dyke, Cau, Escuillié and Godefroit
The ostrich-size Gargantuavis philoinos, was known from France,
dating back from the Late Cretaceous near
the end of the Age of Dinosaurs. However, it was uncertain whether or not it
was the lone exception among its puny relatives. Now another has popped up in Central Asia , revealing giant birds were no flukes.
"Big birds were living alongside Cretaceous non-avian
dinosaurs," researcher Darren Naish, a vertebrate paleontologist at
the University of Portsmouth in England
Naish added, "Badger-sized mammals, big, diverse land-living crocs
and, we now know, really big birds all lived alongside non-avian dinosaurs in
parts of the Cretaceous world." He and his colleagues named the bird
Samrukia nessovi — "Samrukia" after the samruk, the mythological Kazakh phoenix, and "nessovi"
after Russian paleontologist Lev Nessov.
The toothless lower jaw came from a dry, hot, hilly site in Kazakhstan,
though when this creature was alive — about 80 million to 83 million years ago
— the area was a floodplain crisscrossed by big meandering rivers.
The size of the fossil suggests the bird's skull was about 12 inches
(30 centimeters) long.
There is no way to tell from the fossil's structure or thickness
whether the bird could fly. Based on its estimated size, the researchers
calculate that if the creature was flightless, it probably stood 6 to 10 feet
(1.8 to 3 meters) tall, about as big as its counterpart Gargantuavis philoinos;
if it flew, it probably had a more than 13-foot (4 meter) wingspan.
"We can now be really confident that Mesozoic terrestrial birds
weren't all thrush-sized or crow-sized animals — giant size definitely evolved
in these animals, and giant forms were living in at least two distinct
regions," Naish said. "This fits into a larger, emerging picture —
Mesozoic birds were ecologically diverse, with lots of overlap between them and
modern groups."
The area has yielded a diverse assemblage of other fossils, and
"Samrukia was conceivably in danger from tyrannosaurs,
dromaeosaurs and other predatory dinosaurs of the region," Naish
said. Other creatures in the area included armored dinosaurs, duckbilled
dinosaurs, other birds, turtles, salamanders and freshwater and brackish-water
sharks.
It remains uncertain whether Samrukia was predatory, herbivorous or
omnivorous. "The lower jaws don't reveal any obvious specializations for,
say, dedicated plant-eating, or feeding on aquatic prey — if I had to guess,
I'd say it was a generalist, but this is just a guess," Naish said.
"The main thing we can hope for is new material that will provide more
information on this bird — it would be great to know what role they were
playing in these Cretaceous ecosystems."
The scientists detailed their findings online Aug. 10 in the journal
Biology Letters.
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