robert feranec curator of vertebrate paleontology, nysm
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Robert FeranecCurator of Vertebrate Paleontology, NYSM
TOTALLY AWESOME: Extreme Evolution in Mammals—YEAH!! (with fist pump)
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Who’s the Biggest?
Who’s the Smallest?
Who’s the Baddest?
Best Common Name?
Best Scientific Name?
Who’s the Biggest?:Paraceratherium
•Age: 30 million years ago•Height: upto 23 feet tall (15 feet at shoulder)•Weight: upto 20 tons
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Who’s the Smallest?:Batodonoides
•Age: 53 million years ago•Height: small•Weight: 1.3 grams
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Best Scientific Name?:Sunkahetanka pahinsintewakpa
•Age: 28 million years ago•Weight: 20 kgs
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Hesperocyonidae (distant canid relative)
Best Common Name?:Gunther’s Dik Dik
•Age: Modern•Height: upto 40 cm•Weight: upto 5 kgs
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EXTREME?
Head Gear
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Why Head Gear?
Defense:
Combat:
Mate Recognition:
Ornamentation:
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Differential survival and reproduction
Sexual SelectionCertain evolutionary traits are the result of
intraspecific competition
Intrasexual Competition: Generally Male-Male competition, female mates with the “winner”
Intersexual Competition: Female Choice
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Types of Head Gear?
Ossicones:
Horns:
Antlers:
Pronghorns:
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Head Gear: Ossicones
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Head Gear: OssiconesFossils
Sivatherium~8,000 years ago
Samotherium~4 million years ago
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Head Gear: Horns
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Head Gear: HornsFossils
Hoplitomeryx
Syndoceras Synthetoceras
Bison latifrons
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Cranioceras
Head Gear: HornsFossils
Arsinoitherium (from Egypt)Age: 35 Ma
Height: ~7 feet at shoulder
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Head Gear: HornsFossils
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Head Gear: HornsFossils: Brontotheriidae
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Mylagaulid rodentsWhy do they have those crazy horns?
30-5 MaNorth America
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Mylagaulid Ecology• Herbivorous• Body size:
~ 0.5-5 kg.• Fossorial
(burrowing), but how?
• One of the only fossorial animals with horns
Mill
ions
of y
ears
ago
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Fossorial adaptation in rodents
Figure from Stein 2000
Scratch digging
Chisel tooth digging
Head lift digging
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Head digging in mylagaulids
Features consistent with head-digging:
• Thickened, projecting nasal bones
• Tall, forward-tilted occipital plate
• Shortened skull
• Powerful forelimbs
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Likely evolved from head-lift diggers
Why horns?
Possible uses of horns:
• Species recognition
• Digging
• Sexual display/combat
• Defense
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Horns : digging implement
In favor:• Higher occipital plate with
taller hornsAgainst:• Position, orientation of
horns• Change in horns through
time• Increases force needed to
dig• CONCLUSION: unlikely
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Horns : sexual display/combat
• Not sexually dimorphic
• Lack of visual ability
• Display useless underground
• Orientation of horns
• CONCLUSION: unlikely
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Horns : defense
• Passive or active defense
• Predator diversity: mustelids (weasels and stoats), snakes?
• CONCLUSION: Likely, consistent with available evidence.
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Horns…or Not Horns
CoelodontaLate Pleistocene (~20,000 years ago)
Europe
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NOT “true” horns
CoelodontaLate Pleistocene (~20,000 years ago)
Europe
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Horns…or Not Horns
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Horns
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Horns…or Not Horns
Narwhal (modern)
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NOT Horns
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Head Gear: Pronghorns
Antilocapra americana
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Head Gear: PronghornsFossils
Merycodus15 Mya
Ramoceros12 Mya
Ilingoceros8 Mya
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Head Gear: Antlers
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Head Gear: Antlers
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Head Gear: AntlersFossils
Megaloceros giganteus~10000 years ago
•Each antler is 6ft long
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Antlers and…
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Antlers and…Saberteeth!!!
MoschusModern
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Why Head Gear?
Defense:
Combat:
Mate Recognition:
Ornamentation:
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Evolution of saberteeth
Thylacosmilus
SmilodonEusmilus
Machaerodus
Machaeroides
Homotherium
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From Akersten 1985
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Homotherium Smilodon
Is the evolution of the sabertooth convergent evolution or parallel evolution?
Convergent Evolution vs. Parallel Evolution?
Convergent Evolution: describes the acquisition of the same biological trait in unrelated lineages.
Parallel Evolution: the development of a similar trait in different not closely related species (that is in species of a different clade), but descending from the same ancestor.
Question: How do we distinguish how closely an organism is related?
How to Solve this?
Hall (2003) Biological Reviews
Question: How do we distinguish how closely an organism is related?
How to Solve this?
Convergence: Similarity arising through independent evolution having different developmental pathways
Parallelism: A feature present in closely related organisms but not present continuously in all members of the lineage, and uses similar developmental pathways.
Hall (2003) Biological Reviews
Evolution of saberteeth
How do they develop?
Thylacosmilus Machaerodus
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You are what you eat…and drink
Isotopes in modern precipitation
18O
SM
OW
AugustJanuary January
FLAGSTAFF, AZ 1961-1963
From IAEA GNIP Database
+18O
-18O
Oxygen Isotopes(Isotope: same # of P, E- but different # of N)
+18O
-18O
Summer Summer
Winter
Predicted cyclicity in oxygen isotope values of enamel carbonate
TipBase
+18O
-18O
TipBase
12 months
Predicted cyclicity in oxygen isotope values of enamel carbonate
25mm 85mm
60 mm
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
0 10 20 30 40 50 60 70 80 90 100
18 O
val
ue
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
0 10 20 30 40 50 60 70 80 90 100
18 O
val
ue
Isotope values for
S. fatalis
Distance from enamel-root contact (mm)
Average: 66 mm / 12 months =
5.5 mm per month
Feranec, in prep
Panthera tigris2
Panthera leo1
Smilodon gracilis ~12 months
18 months
9-14 months
6.7 mm/month
3 mm/month
9 mm/month
Comparison in Felid canine development
1. Smuts et al., 1978
2. Mazak, 1981
Smilodon fatalis ~18 months5-7 mm/month
Homotherium serum ~15 months2.5 mm/month
Panthera leo >18 months2.8 mm/month
Panthera atrox >18 months2.9 mm/month
TAXONDURATION
OF GROWTHRATE
Feranec. 2004, 2005, 2008
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Convergent Evolution
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Who’s the Biggest?
Who’s the Smallest?
Who’s the Baddest?
Best Common Name?
Best Scientific Name?
Who’s the Baddest?:2010 Championship
Winner
4. Smilodon populator
1. Ursus maritimus tyrannus
2. Andrewsarchus mongoliensis
3. Daeodon hollandi
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Who’s the Baddest?:
V.
6 ft. tall at shoulderWeighs up to 2000 lbs
4ft. tall at shoulderWeighs up to 1300 lbs
4. Smilodon populator1. Ursus maritimus tyrannusEX
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Who’s the Baddest?:
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Who’s the Baddest?:
Polar Bear Wins!!EXTREM
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Who’s the Baddest?:
2. Andrewsarchus mongoliensis 3. Daeodon hollandi
Height: up to 8 ft at shoulderLength: 11 feet longWeight: up to 2200 lbs.Age: 40 Ma
Height: up to 7 ft at shoulderLength: 12 feet longWeight: up to 2200 lbs.Age: 25 Ma
V.
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Who’s the Baddest?:
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Andrewsarchus mongoliensis Daeodon hollandi
Who’s the Baddest?:
Andrewsarchus Wins!!EXTREM
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Who’s the Baddest?:
Winner
1. Ursus maritimus tyrannicus
4. Smilodon fatalis
1. Ursus maritimus tyrannicus
2. Andrewsarchus mongoliensis
2. Andrewsarchus mongoliensis
2. Daeodon hollandi
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Who’s the Baddest?:
V.
6 ft. tall at shoulderWeighs up to 2000 lbs
Can stand up to 11 feet tall
1. Ursus maritimus tyrannus 2. Andrewsarchus mongoliensis
Height: up to 8 ft at shoulderLength: 11 feet longWeight: up to 2200 lbs.
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Who’s the Baddest?:
Size ComparisonEXTREM
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Who’s the Baddest?:
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Ursus maritimus tyrannus!!!
Thank you
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