Idaho’s Ancient Bird
By Sydney Meng, Golden Eagle Guest Blogger
With their powerful demeanor and massive stature, it is hard to believe the reptiles that roamed the earth more than 150 million years ago evolved into the relatively diminutive birds of today. But extensive research over recent decades, has led scientists to determine that birds are the living descendants of dinosaurs, particularly theropods. Theropods are a large group of two-legged species including Tyrannosaurus Rex and velociraptor, terrifying creatures whose family lines ended after a large meteor struck Earth 66 million years ago. Fossilized remains of dinosaurs ranging from species of the Jurassic to Cretaceous periods offer us a glimpse of how these scaly beings behaved, but the question remains: How did the ancient dinosaurs evolve into the familiar birds we see today?
Feathers?
The first ancient bird scientists recognized is Archaeopteryx, a small magpie sized species living in what is now Germany during the late Jurassic period. This creature dwelled alongside the more reptilian theropods and bore a striking similarity in its skeletal structure to its scaly counterpart, including having a wishbone, breastbones, and crescent shaped wrist bones. Archaeopteryx also held an astounding trait unique to its time: feathers. Simple structured feathers made the creature capable of regulating its body temperature and even flight. However, Archaeopteryx was not a true bird, as it still had the long bony tail and sharp teeth of a reptile.
Early fossil evidence confirms that rather than a sudden transformation from reptile to avian species, the evolution was one of many steps during which species gained both reptilian and bird-like characteristics.
© AMNH/Z. Chuang; courtesy of Peking Natural Science Organization
“A bird didn’t just evolve from a T. rex overnight, but rather the classic features of birds evolved one by one; first bipedal locomotion, then feathers, then a wishbone, then more complex feathers that look like quill-pen feathers, then wings,” says Stephen Brussatte, an expert paleontologist representing University of Edinburgh Scotland. He and his team specialize in examining fossils of a certain lineage related to Archaeopteryx, tracing certain characteristics that blur the line between reptile and bird.
From Ferocious to Nimble
Over the period of time dinosaurs evolved into modern avian species, one of the core changes was how small they would become, a process known as miniaturization. Even before Archaeopteryx existed, theropods started to rapidly shrink in size. It was not until bird-like features became more prominent that large species, such as the T. rex, which weighed roughly the same as an African elephant, rapidly miniaturized to the weight of an average bird today, anywhere between a few hundred grams to a couple pounds. Much of the shrinkage happened in the cranium of avian species, where features such as eyes and the beak became closer together throughout transitional species. A smaller and therefore lighter structure allowed more bird-like species, such as Archaeopteryx, to easily maneuver themselves and fly.
Rapid and Wide Diversification
When the asteroid struck Earth during the Cretaceous period, it wiped out most bird-like dinosaurs, leaving only a few species to evolve into the diverse bird families we see today. It is believed that all land birds descended from carnivorous raptors and birds of prey, such as owls being related to toucans, falcons to songbirds, and the nocturnal nightjar to hummingbirds, as most dinosaurs preferred land over water. In contrast, a single common ancestor gave rise to all aquatic birds, adapting to life near or in water. This is significant because it demonstrates that a small number of ancient transitional species paved the way for all modern birds, highlighting the interconnectedness of avian species and their rapid diversification over the past million years.
Cranes: Today’s Velociraptor
Amongst today’s living dinosaurs, many can agree that one of the most dinosaur-like bird species in Idaho is the Sandhill Crane, with its signature bugling call and towering stature. Cranes, also known as the order Gruiformes, are among the oldest bird species on the planet. Fossilized Gruiformes that have been unearthed come from nearly sixty million years ago, shortly after the meteor hit earth and wiped out most reptilian dinosaurs. These remains have almost identical anatomy as cranes in modern times. While most animals only bear a slight resemblance to their ancestors, Gruiformes have been perfected to survive both the prehistoric and modern environment in which they thrive.
The oldest preserved Sandhill Crane was found in Florida, and it dates to 2.5 million years ago. Other modern bird lineages started approximately 1.8 million years ago. Another crane fossil, located in Nebraska, is of the delicate wing of a Crowned Crane, a slightly earlier ancestor of the sandhills, that lived 10 million years ago. Nebraska is still in the center of most Sandhill Crane migration patterns, and paleontologists and archaeologists alike agree that this Crowned Crane must have been migrating in the same exact fashion as Sandhill Cranes today.
Sandhill Crane by Linda Wentz
A Long Journey to Grace
The evolution of reptilian dinosaurs to modern birds is a reminder of the adaptability of life. Over millions of years, ancient reptiles slowly transformed, evolving from fearsome creatures into the diverse birds we see today. This process did not occur in one day but was a step-by-step transformation. From early feathered dinosaurs like Archaeopteryx to the graceful Sandhill Crane, each step in their evolution tells a story. By reflecting on their long journey, we can appreciate its complexity. These amazing creatures should not be taken for granted, so take a moment to observe the bird life around you. Take in the stunningly unique behaviors, chorus, and presence of the dinosaurs that soar about us.
Sandhill Crane by Linda Wentz
Sources:
https://www.nhm.ac.uk/discover/why-are-birds-the-only-surviving-dinosaurs.html
https://www.nhm.ac.uk/discover/dino-directory/archaeopteryx.html
https://www.scientificamerican.com/article/how-dinosaurs-shrank-and-became-birds/
https://www.montananaturalist.org/blog-post/sandhill-cranes-and-the-orchestra-of-evolution/