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What is a Tusk?
Grubb, P. (2005). "Order Perissodactyla". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 634–635. ISBN 978-0-8018-8221-0. OCLC 62265494.
http://www.childrensillustrators.com/ The word tusk is illustrator-details/philwilson/id=1717/ The function and evolution of slideshow/pag=12/ often an unclear terminology used to describe similar TUSKS appendages across multiple species
http://people.ucalgary.ca/~longair/synagris.html http://www.yukonadventures.com/ Saim Bhatti, Kevin Buretta, Kali Garland, Tyler Warren images/product/walrus2.jpg
What is a Tusk? Tusk vs. Fang
!! “True” tusks are not newly evolved features but modified teeth that have developed specificity over time due to selection pressures of environmental demands (elephants and walrus) and sexual dimorphism (in narwhales).
•! An elongated front tooth, can •! Elongated pair of canines have one, two or four •! They are used for catching •! Is typically a canine, but can also and killing prey be an incisor(elephants). •! Does not grow •! Grows continuously over an continually organisms lifetime •! Slightly curved •! Usually curved, but can also be •! Fighting, defense, hunting straight. •! Tool, mating, defense
http://imagesci.com/img/2013/07/elephant-face-19088-hd-wallpapers.jpg http://savethenarwhals.org/files/2011/04/narwhalpod.jpg http://www.animalfactsencyclopedia.com/image-files/605tigersnarling.jpg
Why is this interesting? Tusk breakdown
!! Tusked animals are prevalent (Elephants, Warthogs, !! There is a seasonal thinning of dentine layers on the tusks. (when Wild Boar, Walrus, and the Narwhal. ) fasting during mating season) !! Made up of tooth dentine and topped with enamel. !! Tusks have historically (and illegally still today) been used as sources of ivory for commercial sale. !! African elephants have diamond shaped teeth
!! “The remains of “Tusk’s offer a unique window into !! There is both soft and hard ivory(dentine) depending on the behavior and evolutionary relationship of geographical location of the tusked animal. extinct species” (Ravosa, Matthew J). !! For elephants tusk grow an average of 17cm per year !! Measurements of oxygen isotope composition in tusk can be used to show growth rate and historical seasonal variation (Kotch, Paul L).
http://www.knysnaelephantpark.co.za/anatomy/ http://www.fws.gov/lab/images/narwhal.jpg
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The Phylogeny of Tusks The Phylogeny of Tusks Class: Mammalia / Clade: Eutheria POLYPHYLETIC GROUP AARDVARKS AARDVARKS CETARTIODACTYLA PERISSODACTYLA RABBITS ANTEATERS PROBOSCIDEA TENRECS CETARTIODACTYLA PERISSODACTYLA RABBITS ANTEATERS PROBOSCIDEA TENRECS CARNIVORA PANGOLINS CARNIVORA PANGOLINS BATS HEDGEHOGS MOLES CAVIES/NUTRIAS PORCUPINES MICE/RATS BEAVERS CHIPMUNKS PRIMATES TUPIAS SLOTHS AMRADILLOS ELEPHANT SHREWS MARSUPIALS BATS HEDGEHOGS MOLES CAVIES/NUTRIAS PORCUPINES MICE/RATS BEAVERS CHIPMUNKS PRIMATES TUPIAS SLOTHS AMRADILLOS ELEPHANT SHREWS MARSUPIALS
http://www.whozoo.org/mammals/mammalianphylo.htm http://www.whozoo.org/mammals/mammalianphylo.htm
The Phylogeny of Tusks The Phylogeny of Tusks Class: Mammalia / Clade: Eutheria Class: Mammalia / Clade: Eutheria TENRECS AARDVARKS TENRECS AARDVARKS CETARTIODACTYLA PERISSODACTYLA RABBITS ANTEATERS PROBOSCIDEA CETARTIODACTYLA PERISSODACTYLA RABBITS ANTEATERS PROBOSCIDEA CARNIVORA PANGOLINS BATS HEDGEHOGS MOLES CAVIES/NUTRIAS PORCUPINES MICE/RATS BEAVERS CHIPMUNKS PRIMATES TUPIAS SLOTHS AMRADILLOS ELEPHANT SHREWS MARSUPIALS CARNIVORA PANGOLINS BATS HEDGEHOGS MOLES CAVIES/NUTRIAS PORCUPINES MICE/RATS BEAVERS CHIPMUNKS PRIMATES TUPIAS SLOTHS AMRADILLOS ELEPHANT SHREWS MARSUPIALS
What about this ancestor? Could be Paraphyletic!
http://www.whozoo.org/mammals/mammalianphylo.htm http://www.whozoo.org/mammals/mammalianphylo.htm
The South American The South American Gomphotheres Gomphotheres Introduction and Results This paper utilizes taxon-characterizing software to generate Reconstructed most possible parsimonius trees for South American elephant parsimonious tree of ancestors. !! Questions elephant lineage. !! When did Gomphotheres arrive into the Americas? !! Did they arrive before they diverged into !! Gomphotheres are a subspecies? !! How did the Family Gomphotheriidae paraphyletic group. belonging to Proboscidea diverge?
!! Three representative S.A. species: !! South American species !! A. peruvium, !! C. hyodon, are a monophyletic !! N. platensis. group.
Mothe, D, et al (2013) The South American Gomphotheres Mothe, D, et al (2013) The South American Gomphotheres (mammalia, Proboscidea, Gomphotheriidae): Taxonomy, (mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography. Journal of Mammalian Phylogeny, and Biogeography. Journal of Mammalian Evolution. 20.1: 23-32. Evolution. 20.1: 23-32.
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The South American The Spread of Gomphotheres Gomphortheres
Reconstructed most parsimonious tree of elephant lineage.
!! Gomphotheres are a paraphyletic group.
!! South American species are a monophyletic group.
Mothe, D, et al (2013) The South American Gomphotheres (mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography. Journal of Mammalian Evolution. 20.1: 23-32.
The Origins of Modern Notes from the paper Elephants
More findings:
•! Evidence of loss of lower set of tusks in some gomphotheres (Cuvieronius hyodon) as they become adults (modern elephants have lost their lower tusks). Hyracoidea (hyraxes) , Proboscideans (elephants), Sirenians •! Curved upper tusks in the South American Gomphotheres (dugongs, manatees), and Tubulidentata (aardvarks) are compared to other descendants elsewhere. four orders closely related orders that possibly originated from ungulates (large hoofed mammals). •! Findings not conclusive to fully explain the origins of Derived from “proboscis” which means trunk gomphotheres in South America.
•! Dietary limitations can effect the way that cause selection for particular molar arrangement (to include tusk prevalence).
Gomphotheres the Other Tusk History Facts precursor species
•! Earliest members of Proboscidea were Moeritherium that lived up to 50 mya had pair of large incisor teeth in both jaws and wer 1 meter tall !! The number of tusks changes over time from four to two.
4+ meters tall ! The sex of an organism can effect tusk use, size, and 1 meter tall ! Large, curved Small tusks growth rate. tusks !! Composition of tusks changes with climate and diet.
!! Size of tusk increases with increase in animal size.
Four Four Two Two Tusks Tusks Tusks Tusks
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African Elephants vs. Diversity vs. Function Asian Elephants
!! African elephants have longer tusks !! Male elephants typically have longer tusks than females but rarely in Asian female elephants their tusks may be longer. !! Asian elephants have shorter tusks if present at all. !! Amebelodon (elephant relative) had two sets of tusks, an upper one !! African elephants have softer trunks with more which was similar to modern elephant’s, and one lower that were flattened and may have been used as shovels. ( rings http://www.jstor.org/discover/10.2307/2400995? uid=3739960&uid=2&uid=4&uid=3739256&sid=21104249616043) lower tusks used ! to break through thick foliage to help eat while upper tusks used in a similar fashion ! Asian elephants have harder trunks with less rings to elephants today
! African elephants have heavier tusks weighing up !! Dugongidae both males and females having tusks while on males show wear and ! tear (http://onlinelibrary.wiley.com/doi/10.1002/ar.20540/full) ( to 175 lbs http://www.ncbi.nlm.nih.gov/pubmed/17516442)
! Asian elephants have tusks weighing up to 110 lbs. !! Babirusa have two different tusks, top for shield and bottom for fighting. ( ! http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2907.1981.tb00245.x/abstract)
Tusk Use Questions
!! Many animals use their tusks as a weapon to use against attackers. !! Q: Between the two existing species Hippopotamus and Whale Genus (http://sysbio.oxfordjournals.org/content/57/6/857.short) Rhinoceros, which species has true tusks? A: Hippos have true tusks. A rhino “horn” is composed of !! Elephants use tusks as tools to strip bark, lift object, and to dig and keratinized skin, not dentine. bore holes. ( http://www.jstor.org/discover/10.2307/2400995? !! Q: The South American Gomphotheres sub-family is a uid=3739960&uid=2&uid=4&uid=3739256&sid=21104249616043) ____phyletic group. A: Monophyletic group. !! Walrus use their tusks to propel themselves on floes of ice. !! Q: Which came first? 4-tusked elephant species or 2-tusked? ! Only male Narwhals have tusks, so they may have a sexual A: 4-tusked species came first, and eventually lost their lower ! set of tusks, leaving just two. component. ( http://www.nrcresearchpress.com/doi/abs/10.1139/z81-319#.U4y_oPldVps) Diictodon sexually dimorphic ( http://rspb.royalsocietypublishing.org/content/270/1511/173.short)
Bibliography
Mothe, D, et al (2013) The South American Gomphotheres (mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography. Journal of Mammalian Evolution. 20.1: 23-32.
This paper is our primary research article which describes software generated propositions on the pattern of divergence taken by the Gomphotheres family as it migrated into South America from Asia. This paper focused on changes in teeth (tusk) composition between closely related species of elephant ancestor.
(2014) Kruger National Park. – SANParks. N.P., n.d. Web.
This website includes information and images related to the change in tusk size for elephant ancestors over evolutionary time.
Grubb, P. (2005). "Order Perissodactyla". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 634–635. ISBN 978-0-8018-8221-0. OCLC 62265494.
This paper includes images that reference specific tusked species relevant to our presentation.
(2014) Differences between African and Asian elephants. N.p., nd.. Web.
This website illustrates some differences between existing male and female tusk morphology in elephants.
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