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Claws, Nails, Hooves, Horns, and Antlers

Mammalogy (Fall 2013 Althoff - reference FDVM Chapters 6 & 20). LEC 14. Claws, Nails, Hooves, Horns, and Antlers. Claws, Hooves, & Nails. ______________ tissue Derived from “stratum germanitivum” layer of the _____________ (see Fig. 6.2, p98 - “stratum basale”)

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Claws, Nails, Hooves, Horns, and Antlers

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  1. Mammalogy (Fall 2013 Althoff - reference FDVM Chapters 6 & 20) LEC 14 Claws, Nails, Hooves, Horns, and Antlers

  2. Claws, Hooves, & Nails • ______________ tissue • Derived from “stratum germanitivum” layer of the _____________ (see Fig. 6.2, p98 - “stratum basale”) • In STRATUM BASALE, cells continuously divide and are pushed ____ by cells produced below them. Lack of ________________ from reduction of capillaries results in less metabolic activity

  3. FDVMK p98, Fig. 6.2 DERMIS

  4. Keratin • _________ produced by the epidermal cells • a “coiled” protein • ___________ • when mature, it is ________ tissue

  5. Claws • Most “_________” of keratinized structures • Occurs at the ______ of the digits • Grows _____________ • Consist of 2 parts: a) b) POLAR BEAR SIBERIAN TIGER

  6. UNGUIS--dorsal, scale-like plate; surrounds subunguis • SUBUNGUIS-- ventral

  7. Nails • Specialized “claws” • Found only among in ___________ • Facilitate better grip, more precise object manipulation by hands & feet • Only cover _________ surface • Co-evolved: __________________ _________________ in the dermis at the ends of digits of primates

  8. Hooves • Specialized “___________” • Found only among perissodactyls and artiodactyls • Unguis _______________ surrounds the subunguis • Adaptation combined with ___________ in number of digits • Constantly wears away slowly at ________ surface

  9. Basics....Generalities • Antlers are _________ annually • Horns are ___________ annually • Ungulates only ones with horns or antlers • Perissodactyls _________ have • Artiodactyls _______ have

  10. Perissodactyls • Examples: Horses, tapirs, rhinoceros • Exception: rhino “horn” is or ________ origin and lacks a bony core

  11. Rhino -- an exception (RHINOCEROTIDAE) • ____ bony core • ____ keratinized sheath • Keratinized fibers • ____ attached to bone “fused hairs”

  12. FDVMK p98, Fig. 6.2 DERMIS

  13. DERMAL PAPILLA--composed of blood and nerves which service follicle

  14. Artiodactyls • Two major groupings between ungulates showing major differences in “horns” vs. “antlers” Giraffidae vs. Cervidaevs. Bovidae/Antilocapridae

  15. Giraffe (GIRAFFIDAE) • Bony core (ossicone) • Hair-covered epidermis (skin) • Fused to cranium

  16. Giraffe OSSICONES

  17. Deer, Elk, Moose (CERVIDAE)

  18. Cervids - ANTLERS • Made of _______ • Usually ____________ • Supported on “___________” -- raised extension of _________ bone • ___________ …exceptions: a) caribou (reindeer)--both sexes b) Chinese water deer--none • Velvet--________, highly ____________ skin.

  19. Cervids - ANTLERS…con’t • Aside from __________ tissue, fastest growing tissue known • Antler size and number of tines function of: a) b) c) • Shed ___________ • ____________ antlers: caribou, moose, fallow deer

  20. Pronghorn (ANTILOCAPRIDAE) The “__________” when it comes to horns & antlers

  21. Pronghorn (ANTILOCAPRIDAE)

  22. Pronghorns - “Unique” Horns • _______ core covered by ___________ sheath • “Horn” sheath shed annually, new one grows ______________ • Males have, most females have but they are smaller • Upright horns with ______________ and short, anterior branch (prong) • ______ N. American ungulate with this type of horn

  23. Bison, Gazelle, Oryx, Water Buffalo (Bovidae) Grant’s gazelle

  24. Sichuan takin fringe-eared oryx springbok

  25. Marco Polo Sheep …subspecies of ________which is 1 of 2 thought to be the ancestor/origin of domestic sheep (the other is early mouflon) Kyrgyzstan CHINA Tajikistan Afghanistan Pakistan

  26. Bovids - Typical Horns • Bony core with _________________ • “Horn” sheath over this bony core • “Horn” sheath __________________ shed • Males have, females of some species have • __________________

  27. Bovids: HORNS...con’t • Horns are never branched • Horns are typically long & gracefully curved • Bighorn sheep, Mt. Goats, Bison, cattle in N. America….many, many species in Africa & Eurasia (Fig. 20.24, p400)

  28. Functions of Horns & Antlers • _______________: Show dominance among males and fight for mates, territory during “rut.” Therefore, selection “for” larger, more massive head “ornaments” • ______________: challenge conspecifics, ward off predators

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