Avaceratops: Unveiling the Horned Dinosaur of Montana’s Ancient Landscapes

Avaceratops: Unveiling the Horned Dinosaur of Montana’s Ancient Landscapes

Dive into the world of Avaceratops, a lesser-known but equally fascinating member of the Ceratopsian family. It roamed the lush floodplains of what is now Montana during the Late Cretaceous Period. This dinosaur, whose name pays homage to Ava Cole–the wife of its discoverer–offers a unique glimpse into the diversity and complexity of prehistoric life. With its distinctive horned face, Avaceratops stands as a testament to the evolutionary creativity of nature and invites us to explore its history, lifestyle, and the environment it inhabited millions of years ago.

Avaceratops Key Facts

Meaning of nameAva’s Horn Face
Type SpeciesAvaceratops lammersi
When it Lived83.5 to 70.6 MYA
PeriodLate Cretaceous
EpochMiddle Campanian
Length14.0 feet
HeightApproximately 1.5 feet
Weight1.0 ton
MobilityMoved on all four legs
First Discovery1981 by Eddie Cole
Described by1986 by Peter Dodson
HolotypeANSP 15800
Location of first findJudith River Formation, Montana

Avaceratops Origins, Taxonomy and Timeline

The story of Avaceratops begins with its name, a tribute to Ava Cole that reflects a personal touch in the scientific practice of naming new species. This Ceratopsian’s name, meaning “Ava’s Horned Face,” hints at its distinctive features and the tradition of honoring those involved in dinosaur’s discovery or study.

Illustration of Avaceratops, a small ceratopsid dinosaur from the Late Cretaceous period. This quadrupedal herbivore is depicted with a prominent frill and two short horns above its eyes. The dinosaur's body is robust, covered in scales, and has a greenish hue with patterns suggesting camouflage. The image highlights its unique frill structure and the beak-like mouth used for feeding on vegetation.

Avaceratops is nestled within the Ceratopsid family of the Ceratopsia group, showcasing its place among the horned dinosaurs that have captivated the imagination of scientists and enthusiasts alike. The type species, Avaceratops lammersi, stands as the sole representative of its genus and highlights a unique evolutionary path within dinosaur history.

The timeline takes us back to the Late Cretaceous Period–specifically the Middle Campanian Epoch, dating back approximately 83.5 to 70.6 million years ago. This era marks a time of significant geological and ecological changes, setting the stage for the diverse life forms that inhabited Earth during this period.

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Discovery & Fossil Evidence

Skeleton of A. lammersi, a type species of the ceratopsid dinosaur Avaceratops, displayed in a museum. The fossil exhibits the dinosaur's distinct features, including the large frill, two short horns above the eyes, and a beak-like mouth. The quadrupedal structure and robust ribcage are visible, indicating its herbivorous diet and powerful build from the Late Cretaceous period.
vaceratops lammersi fossil. Exhibit in the Academy of Natural Sciences, 1900
Daderot, Public domain, via Wikimedia Commons

The journey into the past that unveiled Avaceratops began in 1981, when Eddie Cole stumbled upon its remains in the Judith River Formation of Montana. This discovery took place on the Careless Creek Ranch under the watchful eyes of rancher Arthur J. Lammers. The bones of this ancient creature were scattered across what was once a prehistoric stream bed, painting a vivid picture of its final moments. It seems the dinosaur was carried by the currents and eventually came to rest on a sandbar, where it was buried and preserved for millions of years.

The significance of these remains caught the attention of Peter Dodson in October 1981, when he visited Cole’s fossil shop. A subsequent visit to the site with Cole in July 1982 led Dodson to discover additional bones. These finds were later excavated by Anthony Fiorillo starting in 1984. The formal description of the new species was made by Dodson in 1986. This marked the first naming of a Ceratopsid dinosaur since Pachyrhinosaurus in 1950. 

Avaceratops Holotype

The holotype, ANSP 15800, is a partial skeleton that includes parts of the skull, lower jaw, vertebrae, shoulder girdle, and limbs. This specimen is thought to represent a juvenile or subadult individual, though Dodson initially suggested it was nearly fully grown. The reconstruction efforts led by Kenneth Carpenter and the subsequent skeletal mount created by Leroy Glenn have provided invaluable insights into the appearance and structure of Avaceratops. This reconstruction was first displayed in the Academy of Natural Sciences in Philadelphia. It has been instrumental in bringing the dinosaur to life for both the scientific community and the public.

Fossilized squamosal bones of Avaceratops, a ceratopsid dinosaur from the Late Cretaceous period. These bones, shown in four different views (A, B, C, D), display the detailed structure and texture of the squamosal, which forms part of the frill extending from the back of the skull. The highlighted areas indicate key anatomical features used for identification and study.
Squamosal bone (B) compared to those of other basal centrosaurines
Héctor E. Rivera-Sylva, Brandon P. Hedrick, Peter Dodson, CC BY 4.0, via Wikimedia Commons

Further enriching the fossil record of Avaceratops, Paul Penkalski in 1993 referred two squamosals (parts of the skull) of larger individuals to this genus. Additionally, in 1999, Penkalski and Dodson described a second skull. This skull included significant features such as the nose and brow horns, offering deeper insights into the species’ variation. However, the assignment of this specimen to Avaceratops has sparked debate among scientists due to differences in skull morphology and the chronological placement of the fossils, leaving the type specimen as the primary representative of the species.

Avaceratops Size and Description

The description of Avaceratops’ physical characteristics, particularly its skull, reveals a creature of remarkable distinction. Let’s dive in deeper to better understand this fascinating dinosaur.

Size and Weight of Type Species

Size comparison of Avaceratops with a human. This illustration shows the ceratopsid dinosaur Avaceratops lammersi, which lived during the Late Cretaceous period, alongside a human for scale. The dinosaur, depicted in purple, is approximately 2 meters long, highlighting its relatively small size compared to other ceratopsids. The human figure is included to provide a visual reference for understanding the dinosaur's dimensions.
Slate Weasel, Public domain, via Wikimedia Commons

The narrative surrounding the size of Avaceratops has evolved significantly since its initial discovery. Initially, Dodson posited that this dinosaur was on the smaller end of the Ceratopsid spectrum, estimating the holotype to measure about 7.5 feet in length and considering it nearly fully grown. This perspective painted Avaceratops as an exceptionally small species within its family. However, the discovery of a second skull, which may or may not belong to Avaceratops, suggested the dinosaur could reach up to 14.0 feet in length. This revelation, coupled with estimates from 2010 by Paul suggesting a weight of around 1.0 ton for an animal measuring 13.0 feet, significantly alters our understanding of its physical stature.

The Dinosaur in Detail

The frill at the back of the skull is a hallmark of Ceratopsids. It is notably solid in Avaceratops, lacking the fenestrae (openings) found in many of its relatives, except for Triceratops. This results in a more robust and possibly heavier frill. The squamosal, a bone at the front side of the frill, has a large, smoothly curving edge. This is distinct from the stepped edge seen in more derived species. This bone is bisected by a raised area that divides it into two equal halves. This sets Avaceratops apart from its later relatives, where the upper part of the squamosal is typically enlarged.

Initially, the brow horns of Avaceratops were thought to be relatively short. This hypothesis was based more on speculation than concrete evidence, as the holotype did not preserve these features. The discovery of MOR 692 introduced a new perspective with postorbital horn cores that extended about 9.8 inches in length. This finding not only challenges earlier assumptions about the dinosaur’s appearance but also adds a layer of complexity to our understanding of its physical attributes and potential behavior.

The majority of our knowledge about Avaceratops comes from juvenile specimens, which tend to exhibit more ancestral traits. This has implications for cladistic analysis, potentially placing Avaceratops in a more basal position within the evolutionary tree than it might occupy based on adult characteristics. The reliance on juvenile specimens for much of our understanding underscores the challenges in piecing together the life history of dinosaurs and highlights the importance of continued discoveries in the field of paleontology.

Interesting Points about Avaceratops

Avaceratops in its Natural Habitat

This herbivorous dinosaur thrived in the diverse and dynamic ecosystems of the Late Cretaceous Period, a time when North America was teeming with a wide array of plant and animal life. The climate, varying from warm and humid to more temperate conditions, supported lush vegetation, providing ample food sources for this herbivorous dinosaur. Montana was a part of Laramidia in the Cretaceous. This was one of the two paleocontinents that make up modern North America.

Illustration of two A. lammersi dinosaurs. This image depicts the ceratopsid species Avaceratops lammersi, which lived during the Late Cretaceous period. The dinosaurs are shown walking together, highlighting their distinctive frills and horns. A. lammersi was a relatively small herbivore, approximately 2 meters long, known for its short frill and small horns compared to other ceratopsids.
LadyofHats, Public domain, via Wikimedia Commons

The diet of this dinosaur primarily consisted of plants. Its beaked mouth and strong jaw muscles allowed it to process a variety of vegetation. This dietary preference places it within a complex food web, where it likely played a significant role in shaping the vegetation patterns of its environment.

Social behavior in Avaceratops, may have included herd dynamics, suggesting a level of social organization. This, combined with its physical attributes, paints a picture of a dinosaur well-adapted to its environment, capable of navigating both the challenges of predation and the demands of its social structure.

Contemporary Dinosaurs

Brachylophosaurus was a hadrosaur that was significantly larger than our horned friend, Avaceratops. These two would have shared the same stomping grounds, perhaps even crossing paths at a watering hole. This was a neutral zone where size and diet blurred the lines of interaction. Avaceratops’ sturdy frill and sharp beak might have seemed an intimidating figure to smaller creatures, but next to Brachylophosaurus, it was a different story—a testament to the diversity and complexity of their ecosystem.

Then there’s Corythosaurus, another hadrosaur roughly the same size as Brachylophosaurus. It was known for its striking crest. Corythosaurus and Avaceratops, despite their size difference, could have had a fascinating dynamic. Corythosaurus likely focused on high-reaching foliage thanks to its height and specialized feeding habits. Avaceratops however might have scavenged the ground-level greens, both species participating in an ancient form of crop rotation. 

The presence of these giants could have meant tougher competition for Avaceratops when it came to securing food, but it also could have provided a sort of inadvertent protection. Predators might have thought twice before approaching a meal surrounded by such sizable neighbors. This interplay of size, diet, and behavior underscores the interconnectedness of their world, where every creature, big or small, played a role in the delicate balance of their ecosystem.

Frequently Asked Questions

When was this dinosaur discovered?

It was discovered in 1981 by Eddie Cole in Montana.

What does its name mean?

The name means “Ava’s Horned Face,” named after Ava Cole.

What did this dinosaur eat?

It was an herbivore that used its beak to eat the vegetation of the Late Cretaceous.

How did it move?

It moved on all four legs, a stable and sturdy locomotion for large animals.

Where were its fossils found?

Fossils have been found in the Judith River Formation of Montana


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 Avaceratops. 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, 02-14-2024

Featured Image Credit: Nobu Tamura, CC BY 3.0, via Wikimedia Commons

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