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

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Character states: Proboscidea Hyracoidea Sirenia

Carpal & tarsal bones x x x

Short, hoof-like nails 5/4 or 4/3 4 /3 4/

No clavicle x x x

Pectoral mammaries x x x

Abdominal testes x x x

“Horizontal molariform

tooth replacement x x x

Similarities among the Subungulates

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

Dugong

Steller’s Sea Cow (extinct)

Dugongidae

Trichechidae

W. African Amazonian

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

• 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

West Indian Manatee

Characteristics of Endangered Characteristics of Endangered Species :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

• 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?

Natural History of Manatees