Cenozoic Birds and Origin of Mammals

Juramaia

"Jurassic Mother" arguably the oldest placental mammal from late Jurassic -oldest/first mammal

Pineal foreman

"Third eye" that senses daylight and tunes circadian rhythm & metabolism to seasonal changes

Paleogene Period

Age of the modern mammals. This is the time when most modern say mammals first appeared.

Multituberculates

An extinct group of rodent-like animals that were most common Mesozoic animals that eventually got replaced by rodents

Pelycosaurs were replaced by Therapsids, which got replaced by mammaliaforms & Cynodonts. What replaced mammaliaforms & cynodonts?

Mammals

Eutherians

Mammals that give live birth, have a more efficient placenta (derived placenta), and contain true mammary glands

marsupials

Mammals whose immature offspring complete their development in an external pouch. ex. Kangaroos

Relative to eutherians, marsupial infants spend ________ time in the pouch suckling.

More I.e. The baby in the Marsupials comes out very early so it spends more time developing in the pouch after birth

Were all terror birds carnivores?

No, despite its name, not all terror birds were Carnivores ex. Diatryma

Were all Cenozoic birds small?

No, some Cenozoic birds were huge Ex. Argentavis and Phorusrhacos

Were all large birds in the Cenozoic flightless?

No, some giant birds flew ex. Argentavis and Pelagornithids

Hadrocodium

One of the first mammals, had an inner ear like ours

All of the marsupials are native to Australia except __________.

Opossum

What is another name for Eutherians?

Placental mammals

What are the only 2 egg laying mammals (Monotremes)?

Platypus and Echidna

What happened to retaining heat from exhaled air when going from pelycosaurs —> therapsids —> cynodonts —> mammaliaforms ?

Secondary palate and nasal turbinate arose

What happened to fur, whiskers, olfaction, and brains when going from cynodonts —> mammaliaforms —> mammals?

The brains and olfactory got larger

What happened to chewing and biting as we move from cynodonts —> mammaliaforms —> mammals?

The teeth became more complex and precise to a point where the teeth now interlock with each other.

How did homeothermy change from pelycosaurs —> therapsids —> cynodonts —> mammaliaforms? What happened to pineal foreman?

Thermoregulation became uncoupled from the environment overtime and the organism got better at thermoregulating Pineal foreman: The pineal foreman got smaller until it eventually went away in mammaliaforms.

When did mammals first appear?

Triassic Period in the Mesozoic era

T/F: Cynodonts had whiskers.

True

T/F: Pineal foremen is still found in reptiles today.

True ex. Some frogs and snakes

Marsupials and eutherians both have _________ _____________ _________ that the infants suckle on.

True mammary glands

T/F: There were herbivore and insectivore pelycosaurs.

True, (they varies in teeth and sail structures)

T/F: Early mammals were rodent like and very small.

True, some such as Hadrocodium were small as a paper clip

T/F: Mammals were living alongside dinosaurs.

True, the early mammals were small and mostly hid underground to prevent being eaten by the big asz dinosaurs.

T/F: Whales went back from land to sea.

True, they initially had legs and walked on land

T/F: As apposed to reptiles such as crocodiles, mammals such as bats have teeth that meet precisely.

True, when mammals bite, there is little to no gaps between the teeth.

choanae

posterior nasal apertures, this it the other end of the nose that opened into the mouth and went further back over time

secondary palate

roof of mouth; separates the oral cavity from the nasal; mammals can breath while they eat; young could breath through the nose while nursing

circadian rhythm

the biological clock; regular bodily rhythms that occur on a 24-hour cycle

olfactory bulb

the first brain structure to pick up smell information from the nose

Morganucodon

the first mammal that appeared in the Triassic; had hair, gave live birth, was warm blooded, looks like a little shrew or rat

Neocortex

the part of the brain that controls higher cognitive function; the cerebrum

Homeothermy

thermoregulation that maintains a stable internal body temperature regardless of external influence

T/F: Humans are marsupials.

False, they are Eutherians

T/F: Monotremes have true mammary glands.

False, they have modified sweat glands that they use to expel their milk

What happened to locomotion and breathing as we move from pelycosaurs —> therapsids —> cynodont —> mammaliaforms ? (What about ribs?)

-The limbs became more upright, which allows the animal to breath and run at the same time. -The lumbar ribs reduced to being only around the lungs and a diaphragm arose.

How many pulses of size increase occurred for the brain through out time?

3 pulses of size increase

T/F: Pelycosaurs and therapsids had fur and whiskers.

False, fur and whiskers first showed up in cynodonts, which came after therapsids

T/F: Marsupials contain a true placental that is more efficient.

False, their placenta is basal and less efficient

Mammals have heterodont teeth, when did heterodont teeth first arise?

Cynodonts

Which of the following first had whiskers and fur: Pelycosaurs, therapsids, cynodonts, mammaliaforms, mammals

Cynodonts

Put the following from smallest brain size to largest: mammals, cynodonts, mammaliaforms

Cynodonts, mammaliaforms, mammals

When did most of the modern mammals (except elephants) fist appear?

During the Paleocene of the Cenozoic era

Monotremes

Egg laying mammals

T/F: Eutherians have longer a period of suckling than marsupials.

False, eutherians have a shorter period of suckling

In what 3 organism did the 3 pulses of size of brain increase occurred?

Hadrocodium, mammaliaforms, and mammals

What happened to the jaw and middle ear as we move from pelycosaur —> therapsid —> Cynodont —> Mammaliaforms?

Jaw: The lower jaw eventually only consisted of dentary instead of articular, angular, and dentary. I.e.: Jaw only made up of 1 bone instead of 3 Middle ear: The angular and articular bones became the stapes/ear bones

Cynodonts

were mammal-like reptiles that had various combinations of mammalian and reptilian characters. -had whiskers