Module 12 Flashcards
Proboscids
Understand the evolutionary history of proboscis, including links to hyraxes and sirenians, and their role in the broader context of mammalian evolution.
Explore the phylogenetic relationships of proboscideans, highlighting the development and diversification of this group from the late Eocene through the Miocene.
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Examine the reasons why proboscideans (and other terrestrial herbivores) became so large prior to major extinction of megafauna in the late Pleistocene.
Increased fitness with increase of body size (linear relationship).
According to metabolic scaling laws, this large size is possible because their metabolism slows as their body size increases (decreasing energy demands).
“An elephant is 200,000 times larger than a mouse, but has a mass-specific metabolic rate 1/12 as great”
Study the molecular adaptations of modern elephants and extinct proboscids, including genomic insights into the Woolly Mammoth’s arctic adaptations.
Genomic insights: Comparative studies reveal Arctic adaptations in Woolly Mammoths, including genes linked to thermoregulation (e.g., FOXI3 for hair growth) and fat metabolism.
Thermal adaptations: Mammoths evolved cold-climate traits absent in modern elephants, such as thicker fur and fat storage mechanisms.
Phylogeny: Ancient DNA from Notiomastodon and mammoths helps reconstruct proboscidean evolution, showing divergent lineages.
Paleogenetics: Total-evidence analyses combine fossil and genetic data to clarify adaptive differences between Arctic and tropical proboscideans.
Discuss current threats to extant proboscids, including poaching and habitat loss, with an emphasis on the conservation status of African and Asian elephants.
Elephants are almost invulnerable to predation. Their biggest threats are other elephants and poachers of course.
African elephants at a much greater threat; likely due to asian elephants lending themselves to domestication much easier and thus being kept alive by people.
Bleak future for African elephants
Hyraxes display convergent evolution with _______.
rodents
* they kind of look like a cross between a rodent and a horse
Who is Desmostylus?
A hippo-like herbivore and a less-well-known relative of the elephants and sea cows.
Late Oligocene sub epoch through the Late Miocene sub epoch (28.4 mya to 7.250 mya) and in existence for approximately 21.2 million years.
- webbed feet
- beginning of tusk evolution
- teeth similar to those of elephants but less ridged
What is unique about proboscis dentition?
Horizontal tooth placement
What anatomical traits of proboscids suggests they were previously adapted for aquatic lifestyles?
- Internal (intra-abdominal) testes (similar to many sirenians)
- mesonephric kidneys
- specialized respiratory systems
What animals are Sirenians?
Manatees, dugongs, and sea cows
What is Proboscidea?
Proboscidea is a taxonomic order of afrotherian mammals containing one living family and several extinct families.
Proboscideans are a group that includes elephants, mammoths, and mastodons.
Barytheriidae.
Barytheriidae is an extinct family of primitive proboscideans that lived during the late Eocene and early Oligocene in North Africa and Oman.
The Barytheriidae were the first large-sized proboscideans to appear in the fossil record.
Summarize Elepante through time.
What proboscidean was first to move out of the water and back onto land?
Moeritherium
List proboscid adaptations.
- lophodont molars (grinding plant material; convergent with selenodont)
- pillar like limbs and fatty pad under feet to support large size outside of water
- trunks for grasping and stripping the leaves from trees; also works as a snorkel
Deinotherium
Deinotherium, is an extinct genus of large, elephant-like proboscideans that lived from the middle-Miocene until the end of the Early Pleistocene.
Paleomastodon (convergent evolution with…)
Palaeomastodon is an extinct genus of basal proboscideans from the Oligocene of North Africa.
Convergent evolution with the wooly mammoth:
Both adapted to similar environments (cold, sometimes wet environments) in different locations leading to shared physical features like thick coats and similar metabolic adaptations. However, it’s important to note that Palaeomastodon lived much earlier than woolly mammoths, belonging to the Oligocene epoch, while woolly mammoths are from the Pleistocene.
What was unique about Gomphoterium?
Gomphotherium is an extinct genus of gomphothere proboscidean from the Neogene of Eurasia, Africa and North America.
Gomphotherium, like most basal elephantimorphs, had an elongated lower jaw which bore tusks; may have been used for scraping bark
Mammoths are most closely related to which modern elephant?
Asian elephant (NOT African elephants, they are different!!)
Mastodons
Mastodons belong to the order Proboscidea, the same order as elephants and mammoths (which belong to the family Elephantidae).
Demonstrated convergent evolution with wooly and columbian mammoth.
- Both were large and hairy distant cousins of modern elephants
- tusks, similar builds/form
But quite genetically separated from mammoths
https://www.amnh.org/explore/news-blogs/mammoth-mastodon-differences
Define Primelephas
Primelephas is a genus of Elephantinae that existed during the Miocene and Pliocene epochs.
Stegodon spp.
Stegodon ganesa was a large, extinct proboscidean (elephant relative) that lived in the Siwalik Hills of India during the Pliocene epoch (5 to 2.5 million years ago). It’s known for its exceptionally large, straight tusks that were closely placed together, with the trunk likely resting on top of them.
Stegodon aurorae is an extinct species of Stegodon known from Early Pleistocene (2.0 Ma – 1.0 Ma) of Japan and possibly Taiwan.[7][8]: 487 It appears to be an insular dwarf species, exhibiting smaller body size than its mainland ancestors.
How can you tell African and asian elephants apart?
Asian elephants have more hair, humped backs, and smaller ears.
African elephants have large ears and swooped backs.
Name four species of mammoths.
(1) Mammuthus primigenius
(2) Mammuthus imperator
(3) Mammuthus trogontherii
(4) Mammuthus columbi
