Post on 05-Jan-2016
description
Order Carnivora ≥11 families, >287 species
•Naturally distributed on all continents (except possibly Australia)
•Morphologically & behaviorally diverse
•Economically important in most countries
•Ecologically important
Order Carnivora
Recognition characters (most/all related to carnivory):
Dental features (present in MOST species): •Carnassial shear: P4/M1 (secondarily lost in some taxa) •Canines large, conical •Most have primitive # incisors (3/3)
Cranial features: •Transverse glenoid fossa •Sagittal crest often prominent, well developed •Large brains, well developed zygomatic archOther features:
•Most are medium-sized•Acute senses (hearing, sight, especially smell)•Most are adept cursors---sprinting•Simple stomach (cecum reduced or absent in most sp.)
Glenoid/ mandibular fossa
C-shaped: strong hinge,minimizes lateral movementand facilitates up & downmovement
(e.g., mustelids)
Omnivores (e.g., bears,procyonids) have more “open”glenoid fossa, permitting lateral movement
Postcranial modifications:
•loss or reduction of clavicles(increases stride length)
•fusion of carpal bones (may add support for cursorial locomotion)
Fusion of centrale, scaphoid, & lunar bonesof wrist
Carnivora
Most non-carnivorans
Non-cursorial taxa(e.g., ursids, procyonids)
Cursorial taxa(e.g., canids, felids)
Increases stride length
Order Carnivora ≥11 families, >287 species
Suborder Feliformia (“cat like”)Felidae (cats & their relatives)Hyaenidae (hyenas, aardwolves)Herpestidae (mongooses)Viverridae (civets, genets)
Suborder Caniformia (“dog like”)Canidae (dogs & their relatives)Ursidae (bears)Mustelidae (weasels, otters, etc., skunks?)Procyonidae (raccoon, coati, kinkajou)Odobenidae (walrus)Otariidae (sea lions)Phocidae (seals)
Pinnipeds
Creodonts†
Feliformia(‘cat-like’)
Caniformia(‘dog-like’)
Creodonts---Fossil carnivorans, late Cretaceous-Miocene
Outcompeted by more “modern” carnivorans?
18 genera, 40 sp.All continents ‘cept Austr.,Antarctica
Felids: “The ultimate killing machines”
Most specialized hunters of the carnivorans, relying almost exclusively on prey that they have killed themselves.
short rostrum=increasedbite force at canines
Panthera Felis& others
“Big” vs “small” cats
terminal phalanx, supporting claw
edge of fleshy sheatharound claw
horny claw
elastic ligament holdsclaw in (retracted)pads
tendon of extensor muscle
middle phalanx
Retractile (=retractable) claws? PROTRACTILE!
tendon of flexor muscle
tendon at wristholding ligaments in place
ligaments of extensor muscle
terminal phalanx
claw
4 genera, 4 sp.Africa, SW Asia
18 genera, 37 sp.Africa, S. & SE Asia
20 genera, 34 sp.Africa, S. & SE Asia
(Herpestidae)
(Herpestidae)
(Viverridae)
(Viverridae)
(Viverridae)
14 genera, 34 sp.All continents ‘cept Antarctica
6 genera, 9 sp.N. & S. America, Eurasia
25 genera, 65 sp.Worldwide ‘ceptAustralia, Madagascar
6 genera, 18 sp.N. & S. America
“Hypercarnivory”---too much of agood thing?
Stenotopic: restricted range of habitats or ecological conditions
Eurytopic: wide range of habitatsor ecological conditions
Hypocarnivory
Mesocarnivory
•reduced molars & non-carnassial P’s (=reduced grinding)•enlarged carnassials & canines•short rostrum•meat-only diet
•unreduced or enlarged molars•reduced carnassials•long rostrum•omnivorous diet
Hypercarnivory
masseter muscle relaxes more, allowingwide open gape
Smilodon (extinctsabre-tooth cat)
Modern felid
SmilodonThylacosmilus(extinct S. Americanhypercarnivorous marsupial)
•Hypercarnivory has evolved several times (and in severalorders)
•Usually correlated with LARGE BODY SIZE...
Cope’s Rule: Evolutionary trend towardslarger body size.
Common among mammals.
Advantages: -Avoid predators-Enhance reproductive success-Improve thermal effiency-Interspecific competition for food-Capture larger prey (prey size often increases over time)
Tradeoff between foraging effort & food acquired imposes energetic constraint.
Smaller carnivores can subist on small prey (e.g., insects, rodents).
Larger carnivores (> ca. 21 g)--small prey not worth the energy expended.
Larger body size leads to HYPERCARNIVORY and overspecialization?
Prey size (cont.)
Hypercarnivory in N. American canids
Canidae---3 subfamilies Caninae Hesperocyoninae† (>28 sp.) Borophaginae† (>68 sp.)
Diverse in Miocene; peak of 25 contemporaneous species. (compare with 7 extant canids in N.S. today)
N. America endemics
Hesperocyoninae†
Borophaginae†
Cope’s Rule
1st appearance ofhypercarnivoroushesperocyonines
1st appearance ofhypercarnivorousborophagines
Millions of years ago
“Constraint” Any factor that tends to slow the rate ofadaptive evolution.
Reversal to more generalized morphology rare inhighly specialized taxa.
Hypercarnivory may lead to “adaptive peak” that can’tbe descended...