Transcript HYRACOIDEA & SIRENIA: Remnants of the Subungulate Radiation

HYRACOIDEA & SIRENIA:
Remnants of the Subungulate
Radiation
Mammalogy - EEOB 625:
10-12 March 2004
Taxon Quiz III: Friday, 12 March, in lecture
Will cover 25 families (posted on website) of
Carnivora, Cetacea, Proboscidea, Hyracoidea,
Sirenia, Perissodactyla, and Artiodactyla
.
Similarities among the Subungulates
Character states: Proboscidea Hyracoidea Sirenia
Carpal & tarsal bones
x
Short, hoof-like nails 5/4 or 4/3
No clavicle
x
x
4 /3
x
x
4/
x
x
x
x
x
x
x
“Horizontal molariform
tooth replacement x
x
x
Pectoral mammaries
Abdominal testes
Horizontal
tooth
replacement
in Sirenia
Hyracoidea of the Ethiopian
• One family with 6 species in Ethiopian & Palearctic
- Locomotion: mesaxonic but climbers more than runners
Adaptive radiation
- Extinction of a diverse group, some as large as tapirs
- Body size? Gestation length (8 months) a clue?
- Convergent with rodents and lagomorphs: “rodent-like”
“lagomorph-like” dentition? : 1/2, 0/0, 4/4, 3/3 li
- Colonial herbivores - rocky desert areas to forests
- low mortality
SIRENIA: Unique among all orders?
• Habitat and diet ________ & _________
• A mere remnant of a once diverse group
(20 genera) of the Miocene
• Distribution: Dugongidae & Trichechidae
• Four extant & one recently extinct species
Trichechidae
Amazonian
W. African
Dugong
Dugongidae
Steller’s Sea Cow (extinct)
SIRENIA: Unique among all orders?
• Habitat and diet ________ & _________
• A mere remnant of a once diverse group (20
genera) of the Miocene
• Dugongidae & Trichechidae compared
• Dugongidae (with forked tails): one species
Dugong of Indonesia (Stellar’s sea cow: extinct)
• Trichechidae: Distribution of 3 species:
W.
African, Amazonian,
and West Indian or Florida Manatee
West Indian Manatee
• One of four species in a declining,
endangered (?) order
• Characteristics of endangered species
• Physical characteristics and distribution
• Habitat requirements & Feeding behavior
• Reproduction: 5-15% of population in 1st year calves
• Major causes of mortality
• Conservation: Recovery Plan & recent issues
• Current status: n ~ 1900, ~ 8% annual mortality
Characteristics of Endangered
Species :
• Adapted to stable, undisturbed
communities
• Low natality and low natural mortality
• Specialized, narrow habitat or
environmental requirements
• Historically restricted in distribution, on
periphery of range or low in density
Natural History of Manatees
• 2-3 meters long, 350-450 kg, no hind limbs
• Former range reduced to Florida & Puerto Rico
• Habitat: Shallow, warm fresh to marine waters
with abundant aquatic vegetation
• Feed 4-6 hrs/day, consuming 25-35 kg/day
• Reproduction: Polygynous,
- 1st breed at 4-6 yrs, every 3-4 years thereafter
- single calf, 390 day gestation, nurse ~1 year
• Is this characteristic of an endangered species?