What the text calls “subungulates”.
Originiated in Africa (and related to the previous three orders we looked at).
Includes three orders that are rather diverse: Hyraxes, Manatees, and Elephants.
(In fairness, it's been known for quite some time that hyraxes and elephants were related).
Order Proboscidea
Everyone knows this group: elephants!
There are three (?) extant species:
Asian elephant, African elephant and the forest elephant.
Recently, genetic analysis seems to show that Forest elephants are a distinct species, but hybrids (w/ regular African elephants) seem to occur regularly.
We seem to be ignoring the “species” concept (which is, admittedly, flawed).
Elephant ancestors can be traced back to the early Eocene (almost 65mya).
Large size and typical locomotion were present by the late Eocene.
Some elephant ancestors are very well known:
Mammoths first show up in the Pliocene of Africa and spread out from there.
Generally thought that humans contributed to the extinction of the woolly mammoth (Mammuthus primigenius), and that is probably still true.
Recent news seems to indicate climate change.
However, this changes with annoying regularity - wait a few years and it'll shift back again.
Entire mammoths have been found frozen in the ice.
Same family (Elephantidae) as modern elephants.
A few more details on elephant evolution are in your text. Let's briefly look at modern elephants:
African elephant (Loxodonta africana) differs from Asian elephant by:
Larger, more vascularized ears.
Different number of ribs.
Bigger.
Trunk is different (tip has two projections instead of one).
Forest elephant is smaller than African and has differing numbers of toes (front and back).
In general, elephants are so big that they walk (or have a running walk). There is some debate about whether they can actually “run” (all four feet of the ground, though this might be redefined for elephants).
African elephant behavior:
Females and young live in matriarchal groups.
Males are eventually kicked out and form bachelor herds.
Females are sexually receptive only rarely - text mentions that low frequency sounds may be very important in advertising condition of female (notifying males).
Asian elephants seem to behave in a similar way.
Have been domesticated for centuries.
Used in construction, transportation, war.
Also important religiously (think of the Hindu elephant God Ganesha).
All (wild) elephant populations are currently seriously endangered.
Primarily due to poaching, but habitat loss and human-elephant conflict isn't helping.
Order Sirenia:
Seacows, dugongs, manatees.
Four living species, two genera.
Fifth species went extinct in the mid 1700's.
Most people easily recognize seacows. Are large, hairless, aquatic. Forelimbs are modified into flippers.
Pelvis is reduced, have large horizontal fluke.
Lungs are positioned in such a way to let the animal stay horizontal when feeding.
Manatees (e.g., West Indian Manatee - same species as in Florida) continuously replaces teeth.
(teeth move forward and are replaced by teeth further back)
Sirenians eat aquatic vegetation - some of this is very abrasive. It's also low quality food.
Sirenians are found in warmer areas only (but see below)
Due to slow metabolism (diet related), and the fact (?) that their blubber doesn't insulate them well.
(Really?)
Long gestation (13 months); live up to 70 years.
Sirenians are hunted, and have seen serious declines in populations.
Even in Florida, where manatees are protected, boat - human interactions cause lots of mortality.
Steller's Sea cow:
Used to get very large - had a more northerly distribution.
10m, 11,000 kg. Slow, and always stayed at the surface. Lots of blubber.
Thought that large size and blubber(!) helped Steller's seacow survive further north.
Native people living along the Pacific most likely caused most of the population to become extinct.
In 1741, the St. Peter wrecked on Bering Island.
Population of Steller's seacow had survived there and numbered about 1000 - 2000.
After their rescue, the presence of Steller's seacow became widely known, and Russian ships that were hunting for sea otters and seals started to hunt seacows as well.
Usual story - by 1786 Steller's seacow had become extinct. Order Hyracoidea
Hyraxes
These are mostly small (rabbit size) herbivores, found throughout most of Africa.
Incisors grow continuously, have a cecum to help with digetsion.
Three genera, four species.
Two unrelated species (Heterohyrax and Procavia) often occur together in the same rock outcrops (kopjes) and even share nurseries and care for the young.
Provides many benefits, including increased predator detection.
Interbreeding is impossible due to differences in behavior and penile anatomy.
Don't control body temperature that well, so supplement body heat by basking.
On cloudy days may huddle together to keep warm.
Dendrohyrax (as the name suggests) spends most of it's time n trees, and is more solitary.