Lecture 26 Vertebrates - Mammals Flashcards
Three subclasses of Mammals
-Eutheria
-Prototheria
-Metatheria
5 orders of the subclass Eutheria are
-Carnivora
-Cetacea
-Chiroptera
-Rodentia
-Sirenia
One order of the subclass Prototheria is
Monotremata (platypus and short-beaked echidna)
Two orders of the subclass Metatheria (Marsupialia)
-Diprotodontia
-Polyprotodontia
The subclass Metatheria of Mammals is also called
Marsupialia
All subclasses of mammals evolved from a
Common reptilian ancestor
Monotremes evolved in
The Southern Hemisphere
Monotremes retained four reptilian characteristics:
-oviparity
-meroblastic cleavage of embryo
-production of venom
-electroreception
There are __ species of monotremes
5
Which monotremes are found in Australia
-platypus
-short-beaked echidna
The echidna has the
Widest environment range of any Australian mammal
The platypus exists in
Freshwater habitats of eastern Australia
Defining characteristics of monotremes (7)
-absence of calcified teeth (have a keratinised dental pad)
-electroreception used to detect prey
-reptile-like stance (limbs held off to side rather than under body)
-cloaca
-oviparity
-no teats (females produce milk through modified sweat glands)
-venom
Crural glands are (4)
-venom glands found on the ankle of male platypus
-can move independently
-evolved independently of reptile venom
-used for defence of territories
Electroreceptors are located
within the skin of bill/beak in platypus and echidnas
The pectoral girdle of monotremes has
Reptilian features: coracoids, epicoracoids, and interclavicle
Monotremes have multiple
X and Y chromosomes