Elephants, Hyraxes, and Sirenians

Paenungulata

Unranked taxon grouping three extant orders.

Proboscidea

Order including elephants, evolved from Condylarthra.

Sirenia

Order comprising dugongs and manatees.

Hyracoidea

Order consisting of hyraxes, small herbivorous mammals.

Afrotheria

Superorder of mainly African mammals including Paenungulata.

Afrosoricida

Order of tenrecs and golden moles.

Macroscelidea

Order of elephant shrews, small insectivorous mammals.

Tubulidentata

Order that includes aardvarks, nocturnal mammals.

Embrithopoda

Fossil order of rhinoceros-like herbivores.

Desmostylia

Fossil order of hippopotamus-like amphibious creatures.

Tethytheria

Group of Sirenians, Proboscideans, and Desmostylians.

Condylarthra

Primitive mammals from which Paenungulata evolved.

Hind-gut fermentation

Digestive process in Paenungulata with prominent cecum.

Elephantidae

Family including African and Asian elephants.

Loxodonta africana

Scientific name for African savanna elephant.

Loxodonta cyclotis

Scientific name for African forest elephant.

Elephas maximus

Scientific name for Asian elephant.

Gestation period

Elephants have a gestation of 22 months.

Calf weight at birth

Elephant calves typically weigh 120 kg (260 lb).

Social structure

Elephants form stable family units and clans.

Tusks

Modified second incisors, present in African elephants.

Dental formula

Adult elephants have 1-0-3-3 teeth arrangement.

Elephant communication

Calves learn through interaction and vocalizations.

Elephant feet

Built like pillars, support their massive weight.

Graviportal

Term describing elephant's weight-supporting limb structure.

Molariform teeth

Elephants have horizontal molar tooth replacement.

Elephant lifespan

Old elephants rely on softer foods as teeth wear.

Elephant ears

African elephants have larger ears than Asian elephants.

Sexual dimorphism

Males generally larger, females mature earlier.

Elephant Trunk

Versatile appendage for manipulation and feeding.

Proboscis

Fusion of nose and upper lip in elephants.

Elephant Feeding

Uses trunk to tear food before ingestion.

Trunk Functions

Tool use, grazing, sensing, and social signaling.

Water Intake

Sucks up to 14 quarts, then sprays mouth.

Snorkeling Adaptation

Trunk allows breathing while submerged in water.

Pleural Membranes

Thick connective tissue replaces vulnerable membranes.

Thermoregulation

Large size reduces caloric needs per kg.

Digestive Efficiency

Absorptive efficiency is low at 40%.

Hyrax Size

Typically 50 cm long, weighing 1.8-5.4 kg.

Territorial Marking

Scent gland used for marking territory.

Hyrax Dentition

Dental formula: 1 0 4 3; no canines.

Microhabitat

Rock outcrops provide temperature and humidity control.

Fossil Record

Hyracoidea appeared over 40 million years ago.

Early Hyracoids

Varied in size from rabbits to rhinos.

Miocene Competition

Bovids pushed hyraxes into marginal niches.

Hyrax Adaptations

Short legs and grooming claws for survival.

Hyrax Habitat

Found in Africa and Middle East rocky areas.

Elephant Feeding Time

Spend 10-18 hours feeding daily.

Defecation Rate

Defecate 150-250 kg per day.

Cecum Size

Elephants have a small stomach, large cecum.

Swimming Adaptation

Elephant trunk functions as a snorkel.

Isotope Analysis

Used to study Moeritherium's aquatic ancestry.

Pleural Cavity

Filled with loose connective tissue in elephants.

Elephant Mobility

Ability to alter environments and relocate.

Hyrax Ears

Small round ears characteristic of the species.

Hyrax Eyes

Bulging eyes adapted for predator awareness.

Sirenians

Closest living relatives of elephants and hyraxes.

Hyrax

Small, herbivorous mammals with rubbery foot pads.

Hyraceum

Medicinal substance from hyrax dung and urine.

Polygamous Mating Structure

One male mates with multiple females, ~17:1 ratio.

Gestation Period

Hyraxes have 26-30 weeks gestation duration.

Sirenia Order

Includes manatees and dugongs, evolved 50 million years ago.

Dugong

Only strictly marine herbivorous mammal, bottom feeder.

Manatee

Freshwater and marine herbivorous mammals, multiple species.

Pezosiren

First known quadrupedal sirenian from early Eocene.

Sirenian Diet

Primarily consists of aquatic vegetation and grasses.

Dental Formula

Dugong: 0 0 2 3; Manatee: 0 0 3 3.

Buoyancy Adaptation

Dense bones facilitate negative buoyancy in sirenians.

Hindgut Fermentation

Hyraxes have a three-chambered stomach with fermentation.

Mating Herds

Manatees form groups for mating, increasing sperm competition.

Cold Stress Syndrome

Occurs below 68°F (20°C), can be fatal.

Feeding Behavior

Hyraxes feed in morning and afternoon, ~35 minutes.

Metabolic Rate

Influenced by water temperature in manatees.

Cecum

Large cecum aids in digestion for hyraxes.

Extinct Sirenians

Includes Steller's sea cow, extinct since 18th century.

Lung Structure

Sirenian lungs are unlobed, extending vertebral column length.

Hemi-Diaphragm

Each lung in sirenians has its own hemi-diaphragm.

Social Behavior

Lead male hyrax guards group during feeding.

Urine Volume

Hyraxes have very low urine volume, conserving water.

Nostrils

Sirenian nostrils are valvular, aiding in breathing.

Molar Replacement

Manatee teeth replaced continuously throughout life.

Dietary Preferences

Hyraxes consume leaves, twigs, fruits, and grass.

Metaxytherium

An early sirenian from the Eocene period.