Birds and Mammals

Flashcards covering key vocabulary and concepts related to bird and mammal evolution, characteristics, and classification.

K-Pg Mass Extinction Event

Occurred 66 Ma ago, likely due to an asteroid impact, causing significant climate change and mass extinction, including non-avian dinosaurs.

Amniotes

A group including reptiles, birds, and mammals, characterized by extraembryonic membranes (amnion, chorion, allantois) and lungs ventilated by negative pressure via the ribs.

Synapsida

A group of amniotes characterized by a skull with a single pair of lateral temporal openings; includes mammals.

Diapsida

A group of amniotes characterized by a skull with dorsal and lateral temporal openings; includes birds and reptiles (excluding turtles).

Theropod Dinosaurs

The direct ancestors of birds, as agreed upon by most paleontologists.

Archaeopteryx

A genus generally considered "the first bird," dating back to ~150 Ma ago (late Jurassic), possessing both reptilian traits (teeth, solid bones, tail) and avian traits (feathers).

Neornithes

The group containing all living birds; stem birds are fossils more recent/derived than Archaeopteryx but not within Neornithes.

Feathers

A key trait of birds, likely evolved from enlarged reptilian scales, featuring an interlocking mechanism thanks to hooks.

Ramphotheca

The external sheath of keratin on a bird's beak, used for preening, feeding, and sometimes as a sensorial organ.

Palaeognathae

One of the two main groups of birds, also called "ratites," including ostriches, emus, tinamous, kiwis, and cassowaries; most are flightless.

Neognathae

One of the two main groups of birds, including Galloanserae (ducks and relatives, landfowl) and Neoaves (all other birds); the order Passeriformes comprises more than half of all extant bird species.

Synapsida to Mammalia

The evolutionary lineage including pelycosaurs, therapsids, cynodonts, and finally mammals, characterized by changes in skull structure, jaw musculature, and dentition.

Heterodont Dentition

A characteristic of mammals involving specialized teeth, including different types of teeth in the same mouth (e.g., incisors, canines, molars).

Diphyodont Dentition

A characteristic of mammals describing teeth that are replaced only once.

Monotremes

An order of mammals including platypuses and echidnas, known for being oviparous (egg-laying) and lacking nipples (secreting milk onto fur).

Metatheria (Marsupialia)

A group of mammals, most of which are found in Australia and South America; their newborns complete development at the teat of the mother.

Eutherians

A group of mammals with placentas, more developed at birth compared to marsupials; major groups diverged rapidly during the Mesozoic.