1. An integrated package?
Natural selection favored increasingly efficient use of energy
Endothermy facilitated nocturnal activity
Endothermy is especially difficult for young
Diphyodonty, lactation, social behavior

2. Teeth
important to be able to capture, ingest, and digest food as efficiently as possible.
High energetic costs associated with higher body T; increased selective pressure for efficient food processing

3. Teeth
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates

4. Teeth
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend,....

5. Don’t know which tooth this IS (tusk only present in males).

6. Researchers at Harvard and Smithsonian cross-sectioned this tooth.

7. narwhal tusks have no enamel. WHY. Seems odd
narwhal tusks have no enamel. WHY??? Seems odd.. Tooth has extremely sensitive surface with millions of tiny nerve endings. Can detect changes in water temp and pressure, and chemicals that enable the whales to gauge salinity---in indication of ice formation---and find fish to eat.

8. Teeth
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend, display,....
SENSORY ORGAN!!!

9. Teeth
Important for understanding ecology of FOSSIL mammals
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend, display,....
Teeth alone often indicative of diet

10. Teeth
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend, display,....
Teeth alone often indicative of diet
Variable BETWEEN major lineages, relatively constant WITHIN species

11. Teeth
Finally, FOSSILIZE well; better than any other tissue type.
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend, display,....
Teeth alone often indicative of diet
Variable BETWEEN major lineages, relatively constant WITHIN species
FOSSILIZE; may fossil species described from teeth alone, often a SINGLE TOOTH!

12. Published last November. Not even sure WHICH tooth this is
Published last November. Not even sure WHICH tooth this is! This is a condylarth, extinct Cretaceous lineage that we believe was outcompeted and eventually replaced by artiodactyls and perissodactyls.

13. Teeth
High energetic costs associated with higher body T; increased selective pressure for efficient food processing
Mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates
Slice, dice, puncture, stab, grind, defend, display,....
Teeth alone often indicative of diet
Variable BETWEEN major lineages, relatively constant WITHIN species
FOSSILIZE; may fossil species described from teeth alone, often a SINGLE TOOTH!
Traditionally given heavy emphasis in inferring relationships, BUT often misleading due to convergence, etc.

14. Crown Root gumline Alveolus (pl. “alveoli”) Enamel: hardest
Enamel is HEAVILY MINERALIZED, 3% organic, composed of crystals of hydroxyapatite.
dentine: Same mineral composition, but 30% organic, so SOFTER
Enamel: hardest
tissue in mammals.
3% organic...
“pre-fossilized”
Crown
gumline
Dentine: same mineral composition,
but 30% organic; softer.
Pulp cavity: nerves & vessels.
Remains open in rootless, ever-
growing teeth (rodent incisors,
some cheekteeth)
Root
Cementum: bony material
surrounding root
Alveolus (pl. “alveoli”)

15. Teeth grow from one of 3 bones
Teeth present in most verts (birds, turtles excluded), and diverse in some groups, but in mammals TEETH RESTRICTED TO 3 BONES: MAX, PREMAX, & DENTARY
Teeth grow from one of 3 bones

16. Tooth replacement
MOST mammals (we’re an exception) are BORN with milk teeth.
ACTIVE GROWN in jaw occcurs when milk dentition present, poor occlusion, but milk doesn't require CHEWING, so OK. MOLARS added after space becomes available.
Living mammals DIPHYODONT (EXCEPT molars!). Ancestral condition for mammals. Most
other vertebrates have POLYPHYODONT dentition.
“Deciduous” teeth replaced by “permanent” teeth.
Replacement timing varies (e.g., shrews)
Morphology often different in deciduous teeth vs. permanent teeth
Sequence of replacement constant w/in species: useful for AGING

18. dC1 Pregnant SUBadult Microgale!
Note looseness of P2 also, as well as several anterior teeth.
dC1

19. 4 basic kinds of teeth
Incisors: Anteriormost, erupt entirely from premaxillary, us. single-root.
Usually used for picking
or grasping, and grooming.
Modified in several ways:
"Chisels": mostly rodents, but some other mammals.
"Tusks" of elephants
"Scalpels" of vampire bats
"Shovels" of hippos.

20. Incisors
Incisors: Anteriormost, erupt entirely from premaxillary, us. single-root.
Usually used for picking
or grasping, and grooming.
Modified in several ways:
"Chisels": mostly rodents, but some other mammals.
"Tusks" of elephants
"Scalpels" of vampire bats
"Shovels" of hippos.
incisors
Anteriormost teeth, grow out of premaxilla, usually single-rooted
Used mainly for picking, grasping, grooming, but heavily modified in
some taxa...

21. Incisors Dog Rodent Lemur incisors
Incisors: Anteriormost, erupt entirely from premaxillary, us. single-root.
Usually used for picking
or grasping, and grooming.
Modified in several ways:
"Chisels": mostly rodents, but some other mammals.
"Tusks" of elephants
"Scalpels" of vampire bats
"Shovels" of hippos.
incisors
Dog
Rodent
Lemur

22. Incisors Elephant Vampire bat incisors
Elephant tusk is definitely an incisor. SEe from eRic seiffert in Sept Use as example of how fossil evidence + phylogeny can provide insites into dental homology
incisors
Elephant
Vampire bat

23. I C P M Incisors Tusk is modified 2nd incisor. How do we know??? 1 3 3
Elephant tusk is definitely an incisor. SEe from eRic seiffert in Sept Use as example of how fossil evidence + phylogeny can provide insites into dental homology
incisors
I C P M 1 3 3
Tusk is modified 2nd incisor.
How do we know???
Elephant

24. Moeritherium
NEW slide in 2008.

25. NEW slide in 2008.

26. NEW slide in 2008.

27. Canine
canine
First tooth in maxilla or at maxillary/premaxillary suture.
All mammals have AT MOST one canine per quadrant
Usually single-cusped (unicuspid), single-rooted (but exceptions)
Generally used for stabbing, holding prey in carnivores (but exceptions)
Often absent (rodents, some artiodactyls) or heavily modified (elephants)
Can be problematic to identify if absent and next tooth is caniniform

28. Canine Cat Moschid deer Rodent canine
First (anterior-most) tooth growing out of maxilla. May even be nested b/w maxilla and premaxilla
canine
Cat
Moschid deer
Rodent

29. Canine Walrus Babirusa canine
Some sources say walrus tusks are modified incisors, but see notes for this lecture.
canine
Walrus
Babirusa

30. Premolars premolars Posterior to canines, rooted entirely in maxilla
Variable: tiny, peglike in some, massive crushing tool in others
Often “molariform,” but generally smaller, less developed than molars
Premolars are replaced, molars aren’t

31. Premolars
premolars
Dog carnassial
pair

32. Molars molars Posteriormost teeth in toothrow
Variable, but late to erupt
Erupt anterior-to-posterior
NOT REPLACED!

33. Molars
Capybara
molars
Shrew
Elk
Raccoon

34. Cheekteeth
premolars
molars
“cheekteeth”
Despite variation in I, C, much of the important functional variation is found in CHEEKTEETH, particularly MOLARS.

35. “Assembly line” for food processing
capture, pick up
puncture
puncture, shear
gulp!
grind

36. “Convergence” within dental arcade:
“incisiform” canine
Philippine treeshrew
“caniniform” incisor
Elk
“molariform” premolar
Sea otter

37. I C P M =44 I C P M =50 Primitive dental formula 3 1 4 3 5 4 1 3 4
PRIMITIVE dental formulas for placental/eutherian mammals and marsupials known from fossil record.
Differences in dental formula are the result of TOOTH LOSS since we diverged from common ancestor.
Placental:
I C P M =44 3 1 4 3
BUT 1st premolar (P1/p1) lost in many living placentals, so maximum
often 3 premolars!!!!!!!
Marsupial:
I C P M =50 5 4 1 3 4

38. Go over order of loss. Lost from front or back. E. g
Go over order of loss. Lost from front or back? E.g., humans have 2 premolars. Are they 3, 4? 1,2? Incisors? Etc.
Also, Nancy Simmons claims that P1 retained in pteropodids...see Jake Esselstyn’s JM paper.

39. I C P M = =44 Primitive dental formula 3 1 4 3 11 Placental:
Used to summarize number of different teeth on upper and lower jaw of mammals
Example of how to use primitive formula to deduce that this is an incisor, not a canine. BUT we can only conclude that it’s I2 or I3. Diastema and/or non-replaced milk teeth useful from here.
Placental:
I C P M = =44 3 1 4 3 11
“caniniform” incisor

40. I C P M = =44 Primitive dental formula 3 1 4 3 11
SO, can USUALLY assume that first premolar encountered is P2. EXCEPTIONS (example in later slide).
P1 absent in MOST, but not ALL, living placental mammal
Placental:
I C P M = =44 3 1 4 3 11

42. Evolution of molars cingulum 3 prominent cusps.
earliest mammals: 3 main cusps in line or slightly triangular; fit b/w space b/w lowers
WOULD BE HELPFUL TO TALK ABOUT HOMOLOGOUS CUSPS IN INCISORS, CANINES, AND PREMOLARS.
ALSO, LABEL THESE CUSPS TO HELP THEM ORIENT THEM WITH THE NEXT.
ALSO, HAVE A SIDE-BY-SIDE COMPARISON, WITH BETTER ORIENTATION, OF THIS TYPE OF TOOTH AND SIMPLIFIED TRIBOSPHENIC.
cingulum
3 prominent cusps.
Mammals of Triassic (early) mammals “shearing” action.

43. “Tribosphenic” molar pattern
triangle expanded, leading to tribosphenic
modern mammal teeth thought to evolve from tribosphenic. BUT FEW LIVING MAMMALS RETAINED IT AS FIGURED.
significance of talonid basin (mortor & pestle). INTERLOCKING of trigon/hypocone with trigonid & hypoconid of lower.
WHY IMPORTANT?---chewing much more PRECISE, EFFICIENT
expansion of STYLAR SHELF.
stylar shelf
(expanded cingulum)
Upper:
Lower:
(compare with
early mammal)

44. Modifications of the tribosphenic molar
Addition of 4th major cusp, the Hypocone (lower: hypoconid)
Quadritubercular or Quadrate or Euthemorphic
tribosphenic
quadritubercular

45. Modifications of the tribosphenic molar
Quadritubercular or Quadrate or Euthemorphic
stylar shelf
(addition of 4th major cusp)

46. Dilambdodont Crests connecting two prominent outer cones
IDENTIFY STYLAR SHELF ON THIS!
(addition of 4th major cusp)
Crests connecting two prominent outer cones
with smaller cones (“-styles”) of stylar shelf
form double-V or W-shape.

47. Zalambdodont parastyle mesostyle LOSS of metacone, metastyle.
Zalamb (metacone lost or greatly reduced)& Dilamb.
IDENTIFY STYLAR SHELF---THIS IS WRONG!
DO A SIDE-BY-SIDE OF THE B&W ILLUSTRATION TO ILLUSTRATE THE LOSS OF METACONE, METASTYLE.
parastyle
mesostyle
LOSS of metacone, metastyle.
Zalambdodont = cusps form single V.
(Stylar shelf is incorrectly labeled on this figure!)

48. Omnivores
Quadritubercular
Bunodont (ROUNDED)
Brachydont (LOW-CROWNED)

49. Herbivores
cheekteeth characterized by primary cusps elongated in an anterior-posterior direction to form crescent-shaped ridges

50. Brachydont vs. hypsidont
brachydont (also "brachyodont"): teeth having relatively low-crowned teeth, usually found in omnivores
hypsodont: teeth having relatively high-crowned teeth, usually found in herbivores

51. Lophodont (herbivores)
lophodont: a tooth consisting of a series of lophs
loph (lophid for lower teeth): a ridge formed by the elongation (and sometimes fusion) of cusps on a tooth
paracone
metacone
hypocone
protocone
anterior
labial

52. Carnassial pair (carnivores)
an efficient shear for cutting meat and tendon. Found in most members of the order Carnivora, but has also evolved convergently in hedgehogs. P4 M1

53. Carnassial pair
metacone
paracone
protocone
anterior
labial

54. example of how to use primitive formula for eutherians to identify loci. In some canids, “P1” present! Know this by using carnassial and canine.

55. “Assembly line” for food processing
capture, pick up
puncture
puncture, shear
gulp!
grind