This is a dinosaur extraordinarily similar to a bird that could elevate itself
Ciento veinte millones de años después de haber planeado entre los árboles de lo que hoy es el noroeste de China, un pequeño dinosaurio emplumado de cuatro alas ha vuelto a la luz con un nombre nuevo: Jian changmaensis. Su hallazgo amplía el territorio conocido de los microraptores, extiende su presencia en el registro fósil y, gracias a una preservación tridimensional extraordinariamente rara, ofrece a la ciencia una ventana inusualmente clara hacia uno de los capítulos más asombrosos de la evolución: el origen del vuelo. En la historia larga de la vida, este fósil recuerda que los cielos no fueron conquistados de una sola vez, sino árbol por árbol, salto a salto.
- Un fósil de 120 millones de años desafía lo que se sabía sobre dónde vivían los microraptores, empujando su rango geográfico cientos de kilómetros más al oeste de todos los hallazgos anteriores.
- La preservación tridimensional del espécimen —una rareza en paleontología— genera una urgencia científica: la mayoría de estos fósiles llegan aplastados, y este abre una oportunidad única para estudiar la mecánica del vuelo dinosauriano.
- El ecosistema reconstruido es inquietante en su precisión: Jian changmaensis cazaba aves primitivas a orillas de un lago antiguo, y los pellets de hueso regurgitado encontrados en la cuenca lo confirman casi sin lugar a dudas.
- La pregunta de por qué solo un microraptor apareció en un sitio tan rico en fósiles de aves tiene una respuesta ecológica: los animales del bosque y los árboles rara vez caen al fondo de un lago para ser preservados.
- El siguiente paso —escanear el ala fósil en detalle— promete datos que podrían redefinir la comprensión del tránsito evolutivo entre dinosaurios y aves modernas.
Un fósil extraído de la Cuenca de Changma, en la provincia china de Gansu, ha llevado a los paleontólogos a identificar una especie de dinosaurio nunca antes descrita. Los investigadores la han bautizado Jian changmaensis, en referencia tanto a la mitología china como al lugar donde fueron hallados sus huesos. El espécimen tiene 120 millones de años y pertenece al grupo de los microraptores, dinosaurios emplumados de cuatro alas estrechamente emparentados con los ancestros de las aves modernas.
El hallazgo es significativo por varias razones. Extiende el rango geográfico conocido de los microraptores más allá del noreste de China, donde se habían encontrado casi todos los ejemplares anteriores, y representa el espécimen más reciente del grupo en el registro fósil. Matt Lamanna, investigador principal del estudio y curador del Museo Carnegie de Historia Natural en Pittsburgh, describió a estos animales como dinosaurios extraordinariamente parecidos a las aves, capaces de planear entre los árboles de manera similar a las ardillas voladoras actuales. Jian changmaensis tenía aproximadamente el tamaño de un búho común, con largas plumas en las extremidades delanteras y traseras que formaban cuatro alas funcionales.
La clave anatómica que confirmó su identidad fue un gran orificio en el hueso coracoide del hombro —la fenestra supracoracoide— presente en todos los microraptores y casi en ninguna otra criatura conocida. Su función exacta sigue siendo un misterio, aunque Lamanna sospecha que está relacionada con la mecánica del vuelo. Lo que sí resulta claro es que este dinosaurio cazaba aves: en la cuenca se han encontrado pellets de hueso regurgitado compatibles con los restos que dejaría un microraptor tras alimentarse.
La preservación tridimensional del fósil —inusual en especímenes de este tipo, que suelen aparecer aplastados— ofrece una oportunidad excepcional para estudiar la estructura ósea del hombro y las capacidades de vuelo del animal. Los investigadores planean escanear el ala fósil para extraer datos que ayuden a comprender mejor uno de los grandes saltos de la evolución: el surgimiento del vuelo en el linaje que condujo a las aves modernas.
A fossil unearthed in what is now northwestern China is forcing paleontologists to reconsider how a peculiar group of small predatory dinosaurs—the microraptors—lived and hunted. The specimen, preserved in rock for 120 million years, belongs to a species never before identified by science. Researchers have named it Jian changmaensis, a name that nods both to Chinese mythology and to the Changma Basin in Gansu Province, where the bones were discovered.
The find matters for several reasons. It extends the known range of microraptors beyond the northeastern corner of China where nearly all other specimens have turned up. It also represents the most recent microraptor in the fossil record, pushing back the timeline of how long these feathered dinosaurs survived. But perhaps most intriguingly, the fossil's three-dimensional preservation—a rarity in paleontology—offers researchers an unusually clear window into how these creatures may have moved through the air.
Microraptors were not birds, though they were close relatives of the ancestors that would become the first true birds, like Archaeopteryx. To look at one, you would not think of the velociraptor from the movies. Matt Lamanna, the lead researcher on the study and curator of vertebrate paleontology at the Carnegie Museum of Natural History in Pittsburgh, described them as extraordinarily bird-like dinosaurs that could glide to some degree. The smallest microraptors were roughly the size of modern crows. Jian changmaensis was probably about the size of a barn owl—somewhere in the middle of the size range for the group. What made them distinctive was their four wings: feathers covered their bodies, and long plumes extended from both their front limbs and their hind legs, creating the appearance of four separate wings. This arrangement likely allowed them to climb and glide from tree to tree, much as flying squirrels do today.
The definitive clue that this fossil belonged to a microraptor and not to one of the many ancient birds also found in the Changma Basin was a single anatomical feature: a large hole in the coracoid bone, part of the shoulder structure. This opening, called the supracoracoid fenestra, is present in all microraptors but almost nowhere else in nature. Its purpose remains unclear, though Lamanna suspects it may relate to flight mechanics. Jian changmaensis possessed an exceptionally long shoulder bone—a trait that, combined with the fossil's overall structure, suggests this dinosaur was capable of powered or assisted flight.
The Changma Basin has yielded over a hundred bird fossils since researchers began systematic work there in 2004, but until now, only one specimen of a non-avian dinosaur. That single microraptor fossil fills a crucial gap in understanding the ecosystem. The basin, 120 million years ago, was the shoreline of a vast lake ringed with vegetation. Among the early birds that lived there was Gansus yumenensis, discovered in 1981, a primitive bird with webbed feet that likely spent time in the water. Jian changmaensis almost certainly hunted birds like Gansus. A previous microraptor fossil was found with bird bones inside its rib cage. And in the Changma Basin, researchers have discovered bone pellets—regurgitated remains similar to what owls cough up after feeding—that match the size and composition of what a microraptor would have left behind.
Why only one microraptor fossil has been recovered from a site so rich in bird remains remains a puzzle. Lamanna's explanation is straightforward: the basin was a lake environment, and the animals most likely to be preserved there were those living in or near the water. Microraptors, by contrast, inhabited the trees and forest margins. They were less likely to end up fossilized in lake sediments. The three-dimensional preservation of Jian's wing is itself unusual—most fossils of this type are crushed flat, making detailed study of bone structure and flight capability difficult. This specimen, by contrast, retained its three-dimensional form, offering paleontologists a rare opportunity to examine the microraptor shoulder in full detail.
The discovery also illuminates why microraptors evolved wings and took to the trees in the first place. Lamanna theorizes that an ecological niche existed for small arboreal predators, and microraptors filled it. Their ground-dwelling relatives were vulnerable to larger carnivorous dinosaurs. By climbing into the canopy and learning to glide, microraptors found a safer way to hunt and survive. The next step in the research is to scan the fossil wing to extract even more information about how these dinosaurs moved through the air—data that will help clarify one of evolution's most dramatic transitions: the emergence of flight itself.
Citações Notáveis
If you saw that thing perched in a tree, you wouldn't think of the Jurassic Park velociraptor. This is a dinosaur extraordinarily similar to a bird that could elevate itself to some degree.— Matt Lamanna, paleontologist and curator at Carnegie Museum of Natural History
This is great—a new fossil of those dinosaurs that were basically on the edge of becoming true birds.— Steve Brusatte, paleontologist at University of Edinburgh
A Conversa do Hearth Outra perspectiva sobre a história
Why does a single fossil from 120 million years ago matter so much? We've found dinosaur bones before.
This one is different because it's preserved in three dimensions, and it comes from a place where we've never found a microraptor before. That tells us these creatures lived across a wider range than we thought, and it helps us understand what they were actually doing up in the trees.
What were they doing up in the trees?
Hunting. Probably birds, mostly. We found evidence—bone pellets, even a microraptor with bird bones inside it. But also, they were evolving. Their shoulders were changing, their wings were developing. They were becoming something new.
Becoming what?
That's the question. They weren't birds yet, but they weren't typical dinosaurs either. They were in between. This fossil helps us see that transition more clearly.
Why would a dinosaur want to leave the ground in the first place?
Safety, most likely. The ground was crowded with larger predators. The trees offered a refuge. Once you're up there, you start to evolve the tools to stay—longer wings, better shoulders, the ability to glide. Over time, that becomes flight.
And this one fossil tells us all that?
Not all of it. But it's a piece. It shows us that microraptors were diverse, widespread, and successful. They occupied a niche that no other animal could. That matters for understanding how birds came to be.