Anchiornis: Discovering a “Near Bird” from the Late Jurassic

In the depths of what is now Liaoning, China, a remarkable creature once flitted through the forests of the Late Jurassic Period. Anchiornis, a small dinosaur with bird-like features, has fascinated paleontologists since its discovery in the early 2000’s. This dinosaur, whose name translates to “Near Bird,” provides a critical link in understanding the evolutionary journey from dinosaurs to modern birds.

Anchiornis lived around 160 million years ago, and its fossilized remains offer a window into a world long past. These fossils, representing dozens of well-preserved specimens, have revealed in exquisite detail the fine feathery plumage in which this dino was covered – a discovery that has profound implications for our understanding of the origins of birds. Join us as we delve into the intriguing details of Anchiornis, exploring its origins, physical characteristics, and the environment it thrived in.

Anchiornis Key Facts

Anchiornis Origins, Taxonomy and Timeline

Anchiornis, whose name translates to “Near Bird,” is derived from the Greek words ‘Anchi’ meaning ‘nearby’ and ‘ornis’ meaning ‘bird’. This nomenclature is particularly fitting, given the dinosaur’s close evolutionary relationship to birds. Its name deftly encapsulates its importance to the study of avian origins.

Taxonomically, Anchiornis belongs to the group Theropoda, a clade of bipedal dinosaurs that includes some of the most well-known and ferocious species, such as Tyrannosaurus rex and Allosaurus. Within this group, Anchiornis is generally classified as an early member of the Paraves clade, a widespread group of feathered theropods that includes modern birds as well as more ‘typical’ non-avian theropods such Velociraptor and Deinonychus. Its type species, Anchiornis huxleyi, honors Thomas Henry Huxley, a 19th-century biologist known as “Darwin’s Bulldog” for his spirited advocacy of Darwin’s theory of evolution.

Anchiornis thrived during the Late Jurassic Period, specifically in the Oxfordian Epoch, which spans from approximately 163.5 to 157.3 million years ago. This era is significant for its diverse array of life forms and the evolutionary advancements occurring during that time. The fossils of Anchiornis provide a snapshot of this dynamic period, helping scientists piece together the evolutionary lineage leading to modern birds.

Listen to Pronunciation

To listen to the correct pronunciation of this dino’s name, check out this video.

Discovery & Fossil Evidence

The first discovery of Anchiornis occurred in the early 2000’s in Jianchang County, Liaoning, China. This region is renowned for its rich fossil beds, which have yielded numerous significant discoveries. The initial specimen, designated as IVPP V14378, was described in 2009 by the renowned paleontologist Xu Xing. This holotype provided crucial insights into the morphology and classification of this unique dinosaur.

Fossil evidence of Anchiornis is particularly noteworthy due to the exceptional preservation of its feathers. Unlike many dinosaur fossils, which often consist only of bones, Anchiornis specimens include detailed impressions of feathers. These fossils have allowed scientists to reconstruct the dinosaur’s appearance with remarkable accuracy, revealing a creature covered in plumage much like modern birds.
Since its initial discovery, hundreds of additional specimens of Anchiornis have come to light. While continuing to support the initial discoveries, each new specimen adds to our understanding of its anatomy and lifestyle. The degree of preservation in these fossils is a testament to the waterlogged, low-energy conditions in which they were buried, offering a rare glimpse into the past.

Anchiornis Size and Description

Anchiornis was a small, feathered dinosaur – about the size of a crow – with a distinctly avian appearance. Its body structure and plumage provide significant evidence of its evolutionary ties to birds. This small theropod was adapted for a life that likely included climbing and possibly some gliding, a precursor to the powered flight seen in later avian species.

Short description of Anchiornis

Anchiornis had a slender body, long legs, and a tail that was likely used for balance. Its head was small with sharp, serrated teeth indicative of a carnivorous diet. The neck was flexible, allowing for a wide range of motion. The vertebrae were lightweight but strong, supporting its agile movements.

The limbs of Anchiornis were particularly noteworthy. Its elongated forelimbs were 80% the length of its body and feathered, possibly used for gliding or aiding in rapid, controlled descent from heights. They may have also been instrumental in providing an additional burst of speed when chasing prey on the ground. The hind limbs, also feathered, were strong and seemingly well-adapted for running. The tail was also feathered, adding stability during movement. 

The preservation of some Anchiornis specimens is so exceptional that scientists have even been able to observe the distribution of melnomes – the pigment cells that give feathers (and hair and skin) their colour. These studies indicate that the plumage of Anchiornis was rather monotone, with grey and black body feathers and white wings speckled with black at their tips. However, the feathers of its head crest may have been a more rusted browny red colour. 

Size and Weight of Type Species

The type species, Anchiornis huxleyi, measured approximately 1.97 to 2.03 feet in length and stood about 0.7 feet tall at the hips. This diminutive size suggests a lightweight build, further supported by its estimated weight of 1.3 to 2.2 pounds. Such a small and light frame would have been advantageous for an arboreal lifestyle, allowing it to navigate through trees with ease.
Various size estimates have been made based on different specimens, but they all fall within this general range. The feather impressions on the fossils also indicate that Anchiornis was covered in a fine, downy plumage, which would have added a negligible amount of weight but significant thermal insulation. These physical characteristics make it clear that Anchiornis was well-adapted to its environment and lifestyle.

The Dinosaur in Detail

Anchiornis stands out due to its distinctive features that bridge the gap between non-avian dinosaurs and birds. Its feathers are the most striking characteristic, showing a variety of types, from simple filaments to more complex structures akin to modern bird feathers. However, the arms of Anchiornis possessed relatively short primary feathers that had rounded, symmetrical tips, unlike the pointed asymmetrical flight feathers of later maniraptorans and modern birds. With its shorter, more rounded “wing” morphology, as well as the lack of a developed keel on the sternum, the jury is still out as to whether Anchiornis would have been a particularly aerodynamic glider, let alone a proficient flier. 

The skeleton of Anchiornis also reveals much about its capabilities and lifestyle. The long, powerful hindlimbs of Anchiornis are similar to closely related taxa that show clear adaptations for running, suggesting a similar behavior in our dino. However, theropods (and birds) adapted for running tended to reduce or lose the feathers on their hindlegs – whereas Anchiornus retained well-developed feathers on its hindlegs. While these may have assisted the arms in guiding its descent when moving between trees, the general picture is of a curious animal with adaptations pointed towards both (proto-) flight and running, while apparently not being particularly proficient at either.  

Notable specimens of Anchiornis have contributed greatly to our understanding of dinosaur-bird evolution. These well-preserved fossils, with their detailed feather impressions, have been pivotal in reconstructing the appearance and behavior of this species. The information gleaned from Anchiornis has implications not only for its own biology but also for highlighting the mosaic nature of the transition from feathered dinosaurs to birds, with evolution trialing many interesting but ultimately unsuccessful “experiments” along the way. 

Contemporary Dinosaurs

The world of Anchiornis was shared with several other fascinating dinosaur species, each contributing to a complex and dynamic ecosystem. Understanding these contemporaries provides context to the environment in which Anchiornis lived.

Xiaotingia, another feathered dinosaur from the same period, shares many similarities with Anchiornis. Both species exhibit bird-like features, suggesting a close evolutionary relationship. Xiaotingia was slightly larger, with a similar “four-winged” body structure adapted for climbing and possibly gliding. The coexistence of these two species highlights the diversity of feathered theropods during the Late Jurassic.

Epidexipteryx, a contemporary of Anchiornis, was a small, feathered dinosaur known for its long, ribbon-like tail feathers. Unlike Anchiornis, which had long pennaceous “flight” feathers covering its arms and legs, Epidexipteryx’s body feathers were rudimentary, whereas its tail feathers were strictly ornamental. This difference in feather function indicates a variety of evolutionary experiments with feathered displays and possible gliding behavior among theropods.

Yinlong, although not feathered, lived in the same general area and time period as Anchiornis. This small ceratopsian dinosaur was herbivorous, providing a stark contrast to the carnivorous diet of Anchiornis. The presence of Yinlong suggests a diverse ecosystem where various niches were occupied by a range of dinosaur species, each contributing to the ecological balance.

Interesting Points about Anchiornis

Anchiornis in its Natural Habitat

Anchiornis lived in a lush, forested environment with a warm, humid climate. The geography of its habitat included dense forests interspersed with rivers and lakes, offering abundant resources. This setting was ideal for what may have possibly been an arboreal lifestyle, allowing Anchiornis to climb and glide through the trees in search of food.

As a carnivore/insectivore, Anchiornis likely fed on small animals, such as insects and possibly small vertebrates. Its long and powerful feathered arms may have also acted as a secondary propulsion system, providing bursts of speed when chasing prey uphill (or up tree trunks). Its sharp teeth and agile body suggest that it was an adept hunter, capable of quick movements and precise strikes. The presence of feathers would have also provided insulation, crucial for maintaining body temperature in varying climatic conditions.

Life expectancy for Anchiornis, like many small dinosaurs, was probably relatively short, with individuals reaching maturity quickly. Social behavior is less understood. However, it is plausible that Anchiornis lived in small groups or pairs, aiding in hunting and protection. Its senses, particularly sight and hearing, were likely highly developed, assisting in navigation and prey detection.

Frequently Asked Questions

Sources

The information in this article is based on various sources, drawing on scientific research, fossil evidence, and expert analysis. The aim is to provide a comprehensive and accurate overview of Anchiornis. However, please be aware that our understanding of dinosaurs and their world is constantly evolving as new discoveries are made.

Article last fact checked: Joey Arboleda, 06-06-2024

Featured Image Credit: Matt Martyniuk, CC BY 3.0, via Wikimedia Commons