Chapter 22.4 & 23 - Basal Mammalian Clades & Therians

Theria

placentals and marsupials

monotremes

egg laying; platypus, echidna.

marsupials

young poorly developed at birth, reared in a pouch, still have a placenta but less extensive than placentals; kangaroo, possum, wombat, koala

Placentals

young well developed at birth. During development sustained by aplacenta; horse, whale, mouse, bat, mole

True

True or False: Monotreme genetics uses 5 pairs of ssex chromosomes

biogeography

Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time

The marsupial trail

Marsupials radiated from North America in two directions: 1) to Australia via South America and Antarctica and 2) to Eurasia and North Africa, where they became extinct during the Eocene. Placentals most likely originated in Laurasia and from there spread to Africa and Americas.

abdominal pouch

where the young are raised having been born very underdeveloped, moving to the pouch and latching onto a nipple.

epipubic bone

bones that supportt the abdominal pouch

Didelphimorphia

About 95 species including the North American Opossum. The South American opossums are small to medium sized, omnivorous and mainly arboreal. Includes the otter-like Yapok, which catches fish

Paucituberculata

7 species of rat opossums. This was a much more diverse group in the past and included the carnivorous, doglike Borhyaenoids

monito-del-monte

What creature is the ole living member of the Microbiotheriidae, a family that was believed to have been extinct for more than 20 million years

marsupial mole

have spades modified out of two claws and like the other “moles” dig tunnels and feed on worms and insects

True

True or False: all three groups of moles are blind, have no visible ears and short or absent tails and are a great example of convergent evolution

True

True or False: Group Peramelemorphia consists of bandicoots and bilbies

boreoeutheria

originated in Laurasia (North America & Asia; Laurasiatheria) and Europe (Euarchontoglires)

atlantogeneta

originated in Africa (Afrotheria) and South America (Xenarthra)

True

True or False: 33 species of lemurs are currently critically endangered

brachiation

Use very long arms and a highly flexible wrist to swing between branches

megachiroptera

fruit bats that have long-muzzled fox-like faces and mainly eat fruits

microchiroptera

bats that have flattened faces, small eyes and large ears.

True

True or False: the group Perissodactyla are odd-toed ungulates

True

True or False: Pangolins lack teeth

artiodactyla

even-toed ungulates pigs, deer, cattle, antelopes, hippopotamuses

cetacea

whales and dolphins

True

True or False: “Traditional Artiodactyls have two or four toes sheathed in hoofs

toothed whales

have homodont dentition; the teeth are used to capture prey, but not for chewing. (e.g. sperm whale, killer whale, dolphins)

baleen whales

feed on smaller prey that they filter using their baleen, which is made of keratinized extensions of the epidermis (e.g., blue whale, humpback whale, sei whale)

corpus luteum

cells that remain at the point of ovulation (release of egg from ovary) produce progesterone to help establish and maintain pregnancy

Monotreme

cloaca as common opening for excretory and reproductive

Therians

2 separate openings (Primate females are an exception with 3 openings: anus, vagina, urethral opening)

baculum

placentals with bone in the penis