Quiz 8: Mammalia

Monoestrus mammals have _________ estrus per breeding season.

1

Mammals and their closest extinct relatives are synapsids, and their skull has

1 pair of openings in the temporal region

Select all of the characteristics of the the class Mammalia.

Very diverse in size and form endothermic

In female mammals, estrus refers to

a period of receptivity to copulation.

Which of the following describes altricial?

blind and naked

The type of placenta seen in marsupials is called a(n) ______ placenta.

choriovitelline

Cenozoic

current era, started 65 million yrs ago. Age of mammals, mammal diversification exploded in the early Cenozoic. Continued during the Eocene epoch, 45 million yrs ago (ice and dry age). And Pleocene epoch glaciations (which ended with the warming of the planet). Simians (55 million yrs ago), apes (23 million yrs ago), Humanoids and chimps diverged 7-10 million yrs ago and the earliest human fossil dates from 4.4 million yrs ago.

What therapsid group survived into the Mesozoic era and was characterized by heterodont teeth, turbinate bones, a secondary palate and the loss of lumbar ribs?

cynodonts

The arrest of the developing embryo at about the 100-cell stage is called embryonic

dipause

Early mammals had_____________dentition, in which teeth are only replaced once.

diphyodont

Early mammals had___________dentition, in which teeth are only replaced once.

dyphodont

________ are examples of monotremes.

echidnas and platypus

The earliest mammals reproduced by laying____________

eggs

In humans and chimps most of the_____________is shed and discharged through the vagina during menstruation.

endometrium

Modern mammals began to diversify during the Cretaceous period and continued the trend into the_________ epoch about 58 million yrs ago

eocene

The young of the earliest mammals probably hatched from eggs in a(n) _________ condition.

immature

Mammals had developed all the novel attributes of modern mammals by the ______ period.

late triassic

Vertebrates of the late Triassic with middle ear bones, hair, and a jaw joint between the dentary and squamosal bones are classified as early_______________

mammals

______ mammals exhibit brief gestation and prolonged lactation.

marsupials

In apes and monkeys the post-ovulation period is terminated by _______.

menstruation

Carboniferous

middle paleozoic, 300 million yrs ago, first reptiles appear.

Devonian

middle paleozoic, 400 million yrs ago, first fishes

Mammals that have only one single estrus during their breeding season are called___________while those having more than one are called____________

monoestrous polyestrous

Platypus and echidnas are examples of

monotremes

Select all of the following that are egg-laying mammals.

monotremes platypus

Living mammals are divided into two clades, the_________ and the ____________

monotremes therians

The living mammals are divided into the clades ________ and _______.

monotremes therians

Early synapsids that resembled lizards and eventually gave rise to the therapsids are called

pelycosaurs.

_________ mammals retain embryos in the uterus during a prolonged gestation.

placental

The structure of the__________roof allows us to identify three major groups of amniotes (synapsids, anapsids and diaosids) that diverged in the Carboniferous period.

skull

The ______ group of amniotes is characterized by a pair of temporal openings in the skull associated with jaw muscles.

synapsid

In kangaroos, during embryonic diapause the embryo in the uterus stops development in response to ________.

the preceding sibling nursing

The only synapsid group to survive the Paleozoic era was the

therapsids

The earliest mammals of the late_________ period were small, mouse-sized animals with enlarged crania, redesigned jaws, and diphyodont dentition.

triassic

True or false: Marsupials have a type of placenta.

true

True or false: Precocial animals are born ready to run with the herd.

true

The evolutionary descent of mammals occurred over approximately ______ million years.

150

Jurassic

200 to 150 million yrs ago. Middle Mesozoic era, age of the dinosaurs. Coexisted with small, mouse-like mammals. Mammals= only synapsids to survive the dinosaurs, diversify during Jurassic and cretaceous.

Triassic

240 million yrs ago, early Mesozoic before Jurassic. Therapsids, with upright limbs, erect gait, increased feeding efficiency due to changes in skull and mandible, and increased cerebellum activity due to coordination of long neck. Diversified into carnivorous and herbivorous species including the Cynodonts (only therapsids to survive the mesozoic era). By the late Triassic, early mammals with all modern mammal characteristics had appeared.

Permian

280-250 million yrs ago, late paleozoic. Marked by the diversification of synapsids (one pair of temporal openings on the skull) which were the closest relatives to mammals. One group, the pelycosaurs (resembled lizards but erroneous, no monophyletic) diversified in the early Permian. Therapsids (only pelycosaurs to survive the paleozoic transition from Permian to Mesozoic).

Silurian

430 millions yrs ago, middle paleozoic era. Coral reefs, first vascular plants, early insects and spiders develop

Ordovician

500 million yrs ago, early paleozoic era. First land-dwelling organisms appear.

Cambrian

570 million years ago, early Paleozoic era marked by the Cambrian explosion that gave rise to representatives of most modern phyla.

There are about ______ species of mammals.

5700

Select all of the following that describe therapsids.

Gave rise to cynodonts Limbs positioned beneath the body Synapsid skull

Select all of the features pf cynodonts that supported a high metabolic rate.

Heterodont teeth Turbinate bones in the nasal cavity Powerful and specialized jaw musculature.

Which of the following is considered an advantage of marsupial mammals over placental mammals?

Investing less energy in young is advantageous in an unpredictable environment. More energy is available to replace lost young.

Cretaceous

Late Mesozoic, 66 million yrs ago. Dinosaur extinction at the end leaves niches open and changes in climate which favor mammal diversification and adaptive radiation.

Placental mammals exhibit__________reproduction.

viviparous