Lab Quiz 2 Flashcards
(50 cards)
Monotremata
Order
- Reptilian features inc. sprawled limbs and egg-laying
- Teeth absent in all adults; may form tooth buds in juvenile platypuses but these disappear soon after birth
- Instead, platypuses have horny plates that are continually growing
- Lacrimal and frontal bones absent
- Jugals reduced or absent, but zygomatic processes of maxilla and squamosal meet to form complete zygomatic arch
- Jaws covered with rubbery, hairless skin
- Large claws on each digit
- Large, hollow spur on the ankle of males (and some female echidnas); venom-secreting gland at base in platypuses
- No nipples on the mammary glands
- Penis bifurcates at the tip and is attached to the ventral wall of the cloaca
- Females have 10 X chromosomes, males have 5 X & 5 Y
- Auditory bullae are absent
- Prominent epipubic bones
Epipubic Bones
Paired bones that project anteriorly from the pelvic girdle into the abdominal body
Identification of Echidnas
Skulls may resemble those of small anteaters or pangolins (which are also toothless and cone shaped)
- Echidnas have a more elevated braincase
- Premaxillae of Tachyglossus are bents lightly upward
- Anteaters have well-developed lacrimal bones (absent in echidnas and pangolins)
- Pangolin skulls tend to be more robust and lack an angular process
Metatheria
Infraclass, contains Superorders:
- Ameridelphia
- Australidelphia
(Total of 7 Orders)
Characteristics:
- Marsupium in 2/3 of living species
- Always more upper than lower incisors (except wombats, Vombatidae - Diprodontia)
- Primitive formula is 3 premolars and 4 molars (reverse of placentals)
- Total number of teeth often exceeds 44
- Diprotodont teeth in two orders
- Canines and first premolars frequently incisiform
- Angular process inflected (projects medially)
- Jugal contributes to mandibular fossa in all marsupials except genus Tarsipes
- Most are plantigrade, some digitigrade
- Hallux lacks a claw in all marsupials
- Simple yolk sac placenta in most, chorioallantoic in Peramelemorphia
- Epipubic bones present in males and females, vestigeal in marsupial moles and Tasmanian wolf
- Two separate uteri with two vaginal canals (temp. median birth canal during childbirth)
- Penis often bifurcate, no baculum; scrotum anterior to penis
- Separate urogenital and digestive openings in most species (exception is Microbiotheria)
Diprotodont
Condition where the lower jaw is shortened and the first pair of lower incisors are very enlarged and elongated
Polyprotodont
Non-diprotodont, or normal tooth condition
Syndactyly
Condition where two toes are fused so the skeletal elements of both are encased within one skin sheath
- Two claws will project from the end of this digit
Didactyly
Condition with no fused digits, opposite of syndactylous
Ameridelphia
Superorder within Metatheria, contains:
- Didelphimorphia
- Paucituberculata
Marsupials from the New World
Australidelphia
Superorder within Metatheria, contains:
- Dasyuromorphia
- Notoryctrmorphia
- Peramelemorphia
- Diprotodontia
- Microbiotheria
Didelphimorphia
Order within Ameridelphia
Opossums
Neotropical region, except Didelphis virginiana, which ranges into the Nearctis
Characteristics
- Most probably omnivorous
- Terrestrial and arboreal, one semiaquatic, some semifossorial
- Marsupium more absent than present
Identification of Didelphimorphia
- Incisors are 5/4, small, peg-like
- Polyprotodont
- Canines are well-developed
- Pentadactyl and no syndactylous digits
- Well developed hallux is clawless and more or less opposable
- Tail prehensile to semi-prehensile
- Frequently have a naked, rat-like tail
May be confused with Microbiotheria or Peramelemorphia (both have five upper incisors)
- Microbiotheria has inflated auditory bullae
- Peramelemorphia has three lower incisors
Didelphis virginiana
Appearance
- Long-haired, scruffy; naked nose and ears
- Rat-like tail is furred at base, then black and naked, then has long white tip
- Five toes on each foot, opposable hallux
- Incisors 5/4
Similar species
- Norway rat is much smaller and has shorter fur, with no fur on base of tail
Habits
- Nocturnal, though sometimes active by day in winter
- Climbs well, uses prehensile tail for balance
- May “play dead” if provoked
- Omnivorous and will eat almost anything
- Solitary
- Seminomadic; dens in hollow logs, rocks, burrows made by other animals
- Female gives birth to 8-16 2g young that attach to one of 13 nipples for 2 months; 3rd month on mom’s back
- May have 2-3 litters per year
Habitat
- Oldfields, forests, agricultural areas, roadsides, suburbs, and urban regions
Status
- Common to abundant
- Frequently roadkill
- Sometimes killed for meat in southern US
Range
- Native from Central America all the way to Southern Ontario
- Introduced widely along the west coast
Paucituberculata
Order within Ameridelphia
Caenolestids - flaplips/shrew-opossums
Neotropical region
Characteristics
- Small and shrew-like
- Feed on invertebrates, plants, fungi and seeds
Identification of Paucituberculata
- Diprotodont
- Incisors usually 4/3
- External membranous flap on both sides of the upper and lower lips
- Marsupium always absent
- Tail long and haired to tip
- Limbs subequal
- Didactylous
- Can be distinguished from Diprodontia because they have 4 upper incisors
- Can be distinguished from mice and shrews due to clawless hallux and flaps on lips
Dasyuromorphia
Order within Australidelphia
Carnivorous/insectivorous marsupials - Tasmanian wolf, Tasmanian devil, numbat
Australian region
Characteristics
- Mostly terrestrial, a few arboreal/semifossorial
Identification of Dasyuromorphia
- Polyprotodont
- Incisors 4/3
- Canines well-developed in most
- Didactylous toes
- Hallux clawless if present
- Marsupium, if present, opens to the rear
- Non-prehensile tail
- Can be distinguished from similar eutherians because of 4 upper incisors, inflected angular process, and clawless hallux
Notoryctemorphia
Order within Australidelphia
Marsupial moles
Australian region
Characteristics
- Fully fossorial
- Live in sandy deserts
- Feed on insects
Identification of Notoryctemorphia
- Dental formula I 3-4/3 : C 1/1 : P 2/2-3 : M 4/4 (T: 40-44)
- Skull conical in shape
- Skin has horny rostral shield
- Claws are very enlarged on third and fourth digits to form spades
- Pinnae and externally visible eyes absent
- Fur silky, pale, iridescent
- Tail short, naked, conical
- Marsupium present
- Vestigial epipubic bones
- Inflected angular process distinguished from eutherians
- Skin unique in having less than 5 digits on forefeet and horny rostral shield (golden moles have small rostral pad but no external tail)
Peramelemorphia
Order within Australidelphia
Bandicoots and bilbies
Australian region
Characteristics
- Terrestrial
- Primarily insectivorous
- Vaguely similar to rabbits in size and appearance
Identification of Peramelemorphia
- Polyprotodont
- Dental formula I 4-5/3 : C 1/1 : P 3/3 : M 4/4 (T: 46-48)
- Incisors have flattened crowns
- Wide space between canines and last incisor/first premolar
- Syndactylous digits on hind feet
- Elongate rostrum
- Skull conical in shape
- Hindlimbs larger than forelimbs
- Reduced number of digits on pes and manus
- Clavicle rudimentary or absent
- Marsupium always present, opens to rear
- Chorioallantoic placenta, but lacks villi seen in eutherians
- Can be distinguished from eutherians by number of upper incisors and inflected angular process
- Skin can be distinguished from others because of syndactylous digits
Diprotodontia
Order within Australidelphia
Kangaroos, wallabies, koalas, possums, wombats, etc.
Australian region
Characteristics
- Vary considerably in size
- Occupy diverse habitats
- Terrestrial, semifossorial, or arboreal
Identification of Diprotodontia
- Diprotodont
- Incisors can be 3/2-3; 3/1; 2/1 or 1/1
- Second and third lower incisors minute when present
- Syndactylous second and third digits of hind foot
- Marsupium always present, opens anteriorly or posteriorly
- Can be distinguished from paucituberculatans (who are also diprotodont) by having less than four upper incisors
- Inflected angular process means marsupials
Microbiotheria
Order within Australidelphia
Monito del monte (only extant species)
Neotropical region
Characteristics
- Opossum-like in appearance
- Scansorial or semiarboreal
- Lives in dense, humid forest
- Insectivorous or faunivorous