As scientists learn that the time period between the present and the development of various species gets longer, the interval between the formation of the earth and the appearance of life is getting shorter.
Archaeopteryx, a descendant of the dinosaurs, was always considered the “first bird,” according to Amy Balanoff of the American Museum of Natural History, a transitional species between feathered dinosaurs and birds. Archaeopteryx lived during the Jurassic period (200 to 145 million years ago). Balanoff and her team studied the brain sizes of more than two dozen species. The results of the study were published in the journal Nature.
The team was looking for connections between dinosaurs and birds. They found that Archaeopteryx wasn’t alone, and wasn’t as bright as some of its contemporaries.
Balanoff’s team used computed tomographic (CT) scanners at the University of Texas, Ohio University, Stony Brook University, and the Museum to get high-resolution images of brain sizes of more than two dozen existing and extinct species, including modern birds, Archaeopteryx, and closely related non-avian dinosaurs, like the tyrannosaurs. They created 3-D reconstructions of the interiors of the skulls. The team not only calculated the volume of each digital brain cast, but also determined the size of each brain’s major anatomical regions, including the olfactory bulbs, the cerebrum, optic lobes, cerebellum, and brain stem.
The distinction between birds and dinosaurs was based upon the characteristic of “hyperinflation.” Although that’s also a term used in economics, here it refers to physical structure: the size of the brain relative to the body. Birds have the quality of hyperinflation. Because they have big brains relative to their bodies, they are endowed with the vision and coordination necessary for flight. This hyperinflation is particularly located in the forebrain. It was thought that reptiles lacked this superior relation between brain and body.
But then, scientists once believed that dinosaurs lacked feathers and furcula (wishbones). They now know that these features first appeared in non-avian dinosaurs.
Several of the other non-avian species were sampled, such as the oviraptosaur and the troodontid. They possessed larger brains relative to body size than did Archaeopteryx. They also possessed birdlike qualities.
The oviraptosaur had a beaked parrotlike skull, and feathers. Troodontidae is actually a family of birdlike dinosaurs, ranging from the Troodon, the largest, to the smallest, Anchiornis. Anchiornis was also the smallest known non-avian dinosaur. Troodontid were distinguished from the rest of the brood by the size of their brains, which incidentally are comparable to those of living flightless birds. Their eyes were also especially prominent and aimed forward, indicating that they had very strong binocular vision. Their ears were also distinctive, in that they had enlarged middle ear cavities, suggesting acute hearing ability.
The conclusion is that if Archaeopteryx was morphologically prepared to fly, then so were other dinosaurs.
The addition of other birdlike dinosaurs suggests that evolutionary qualities may have proliferated much sooner than previously believed. This is similar to the discoveries of humanlike beings at more distant periods of time. If species can be tracked further back in time, then life may have appeared sooner after the earth’s formation than previously known.
“Archaeopteryx” is a combination of two Greek words: archaīos, “ancient,” and ptéryx, “feather” or “wing.” Paleontologists view Archaeopteryx as a transition between dinosaurs and modern birds. It was closer to dinosaurs in that it had teeth, three claws on each wing, a flat sternum (breastbone), belly ribs (gastralia), a long bony tail, and a wishbone. However, like modern-day birds, it had feathers and a lightly-built body with hollow bones.
Discovered in 1860 in Germany, it is sometimes referred to as Urvogel, the German word for “original bird” or “first bird.”
Now it may not be at the head of the bird line.
Archaeopteryx was about the size of a crow. It was about a foot long (30 centimeters) from beak to tail, and probably weighed between 11 to 18 ounces (300 to 500 grams). Although it had a wingspan of about 1.5 feet (0.5 m), if it were able to fly, it would not have flown very far or very well.
Pterodactylus, commonly referred to as Pterodactyls, were better at flying, because their wings were made of skin and muscle membrane. They soared above the earth during the late Jurassic and early Cretaceous periods. The Cretaceous period extended from 145 to 66 million years ago.
Researchers in the Natural History Museum study also examined another factor that is important to flight in modern birds: a neurological structure called the wulst, which is used for the processing of information and motor control. The team identified an indentation in the digital brain cast of Archaeopteryx that might be similar to the wulst seen in living birds. But the indentation is not found in other non-avian dinosaurs, including those that have bigger brains than Archaeopteryx
If birdlike dinosaurs appeared on the earth earlier than expected, then the time from the beginning of the earth to the beginning of life might be shorter than we thought.
By: Tom Ukinski