Euarchontoglires: The Mammals of Intelligence and Adaptation

In a Nutshell: What is Euarchontoglires?

The superorder Euarchontoglires is one of the two major branches of Boreoeutheria, containing some of the most intelligent and adaptable mammals on Earth. This group includes primates (monkeys, apes, and humans), rodents, rabbits, flying lemurs, and tree shrews.

With over 3,500 species, Euarchontoglires is one of the most diverse groups of placental mammals, second only to Laurasiatheria (which includes bats, carnivores, and hoofed mammals). The species in this superorder display an extraordinary range of adaptations, from the arboreal agility of primates to the explosive reproductive success of rodents.

Key Fact: Despite looking very different, primates and rodents are evolutionarily related! Both groups share a common ancestor that lived more than 80 million years ago.

Keep reading to learn more about Euarchontoglires!

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Key Characteristics of Euarchontoglires

Euarchontoglires exhibits several evolutionary, anatomical, and ecological traits that contribute to its dominance among mammals.

Evolutionary Origins

Originated in Laurasia – The earliest members of Euarchontoglires likely lived in North America or Eurasia during the Cretaceous period (~85 MYA).
Rapid diversification after the dinosaur extinction – With the disappearance of large reptiles, Euarchontoglires quickly evolved to occupy new ecological niches.

Anatomical and Physiological Traits

Large brains – Many members of this group, particularly primates, have high intelligence, advanced problem-solving abilities, and social behaviors.
Ever-growing or specialized teeth – Rodents and rabbits have continuously growing incisors, while primates developed highly specialized molars for varied diets.
Arboreal adaptations – Many species, from tree shrews to primates, evolved grasping hands, flexible joints, and strong vision for life in trees.

Reproductive and Developmental Aspects

Extended parental care in primates – Unlike rodents or rabbits, primates invest heavily in long childhoods and social learning.
Rapid reproduction in rodents and rabbits – Some species, like mice, can have multiple litters per year, ensuring high survival rates despite predation.

Major Groups of Euarchontoglires

Euarchontoglires is divided into two clades, each with unique evolutionary adaptations:

Euarchonta (Primates, Tree Shrews, and Flying Lemurs)

This group contains primates and their closest relatives, which evolved grasping hands, enhanced vision, and large brains for arboreal life.

Order Primates – Includes monkeys, apes, and humans, known for their advanced cognitive abilities, social structures, and tool use.
Order Dermoptera (Flying Lemurs) – Gliding mammals with membranes extending from limbs to tail, allowing efficient aerial movement between trees.
Order Scandentia (Tree Shrews) – Small, squirrel-like mammals that share ancestral traits with primates, once thought to be their closest relatives.

Fun fact: The flying lemur (Colugo) is not a lemur at all—it is actually a close relative of primates and has one of the largest skin membranes of any gliding mammal!

Glires (Rodents and Rabbits)

Glires is the most species-rich mammalian clade, containing over 2,500 rodent species and 100 lagomorphs (rabbits and hares).

Order Rodentia – The largest mammalian order, including rats, mice, beavers, porcupines, and squirrels, known for their continuously growing incisors and adaptability.
Order Lagomorpha (Rabbits, Hares, and Pikas) – Similar to rodents but with four incisors instead of two, adapted for high-speed evasion from predators.

Fun fact: Beavers, the largest rodents in the Northern Hemisphere, can completely alter ecosystems by building dams, creating wetlands that benefit countless other species.

Euarchontoglires vs. Laurasiatheria: What’s the Difference?

Euarchontoglires is the sister group to Laurasiatheria within Boreoeutheria. While both groups evolved in Laurasia, they specialized in different ecological roles.

Feature	Euarchontoglires (Tree Dwellers & Gnawers)	Laurasiatheria (Predators & Hoofed Mammals)
Major Groups	Primates, rodents, rabbits, tree shrews, flying lemurs	Bats, carnivores, whales, hoofed mammals, insectivores
Adaptations	Grasping hands, large brains, gnawing incisors	Echolocation, sharp claws, fast running, aquatic life
Common Habitats	Forests, grasslands, urban environments	Oceans, forests, open plains
Diversity	~3,500 species	~3,000 species

Key takeaway: Euarchontoglires evolved for climbing and gnawing, while Laurasiatheria adapted for running, hunting, and aquatic life.

Summary

Euarchontoglires includes primates, rodents, rabbits, tree shrews, and flying lemurs.
It is divided into two major groups: Euarchonta (primates, tree shrews, flying lemurs) and Glires (rodents, rabbits).
These mammals originated in Laurasia and evolved arboreal, gnawing, and social adaptations.
It is one of the two major groups of Boreoeutheria, alongside Laurasiatheria.