Mammalia Infraclass Flashcards

Infraclass Overview

• Mammalia is divided into three infraclasses: Ornithodelphia, Metatheria, and Eutheria.
• Each infraclass is characterized by specific reproductive strategies and developmental traits.

Ornithodelphia

• Represents monotremes, the only group of mammals that lay eggs.
• Includes species such as the platypus and echidna.
• Eggs exhibit leathery shells, and mothers provide milk to hatchlings without teats.

Metatheria

• Known as marsupials, characterized by giving birth to less developed young that typically complete their development in a pouch.
• Examples include kangaroos, koalas, and opossums.
• Marsupial reproductive systems allow for prolonged gestation followed by a short external carrying period.

Eutheria

• Comprises placental mammals, which have a more developed offspring at birth compared to other infraclass groups.
• These mammals connect to the mother through a complex placenta, allowing for extended gestation periods.
• Includes a vast array of species, such as humans, elephants, and whales.

Test your knowledge on the infraclasses of Mammalia with these flashcards. Explore terms like Ornithodelphia, Metatheria, and Eutheria, and understand their unique characteristics such as egg-laying and pouch development. Perfect for students and enthusiasts of biology.