4: LAB EXERCISE KEY
ANT 301 Summer 2007 FUNCTIONAL MORPHOLOGY AND PRIMATE POSITIONAL BEHAVIOR STATION 1: INTERMEMBRAL INDEX SPECIES humerus + radius lengths (A) Cercopithecus mona (mona monkey) xxx H 202, R 200 Ateles geoffroyi Forelimb 402 mm (spider monkey) Propithecus diadema (sifaka) xxx H 188, R 193 Papio anubis Forelimb 381 mm (baboon) KNM-MB VM (mystery fossil) xxx H 360, R 368 Pongo pygmaeus Forelimb 728 mm (oragnutan) Hylobates lar (white-handed gibbon) xxx Tarsius bancanus (western tarsier) xxx H 98, R 96 Eulemur macaco Forelimb 194 mm (black lemur) H 310, R 237 Homo sapiens 545 mm (humans)
femur + tibia lengths (B) xxx
F 194, T 198
Intermembral Index (A/B)100 78.4 103 64.0 93 92 142 129.7 61.0 66 70
Hindlimb 385 mm xxx
F 217, T 177
Hindlimb 394 mm xxx
F 263, T 240
Hindlimb 503 mm xxx xxx
F 143, T 127
Hindlimb 272 mm
F 430, T 345
792 mm
2. Using information from the above table, match the following. __B__ low IM index a. forelimb length = hindlimb length __C__ high IM index b. forelimb length < hindlimb length __A__ intermediate IM index c. forelimb length > hindlimb length __D__ Pongo pygmaeus __C__ Papio anubis __A__ Propithecus diadema __B__ Cercopithecus mona a. b. c. d. leaper arboreal quadruped terrestrial quadruped suspensory primate
3. Why are the ratios for Homo sapiens and Propithecus diadema similar? Explain in functional terms. Both Homo and Propithecus have relatively short forelimbs and long hindlimbs, therefore, a small IMI ( <70). Their hindlimbs play a key role in their locomotor preference in effect, both utilize hindlimb propulsion humans for two legged walking (bipedality), sifakas for two legged leaping (vcl). While both share an IMI < 70, the specimens can be easily distinguished from one
another as a result of their disparate body sizes. Bipeds are relatively large and VCL primates are considerably smaller. 4. What species is KNM-MB VM most similar to in terms of the IMI? KNM-MB is most similar to the terrestrial quadruped in the sample: Papio anubis (baboon). Therefore we might predict that the fossil species represented by KNM-MB VM was also terrestrial and similar to the baboon in aspects of its "niche".
STATION II: OLECRANON-ULNAR INDEX: Understanding the functional morphology of a biomechanical lever system. SPECIES Papio anubis (baboon) Pongo pygmaeus (orangutan) Saguinius fuscicollis (tamarin) Eulemur macaco (black lemur) Dasypus (armadillo) Length of olecranon process (A) 17.3 mm 15.3 mm -------12.1 mm 26.1 mm Length of ulna (B) 198 mm 355 mm ------90.3 mm 41.2 mm Olecranon-ulnar index (A/B )100 8.7 4 11.5 mm 13 63
6. What kind of lever system is indicated by a low OU index (speed or power)? A speedy system. 7. What kind of lever system is indicated by a high OU index (speed or power)? A powerful system. 8. Which primate species is capable of delivering the most speed to its forearm during extension? Pongo pygmaeus. When they are in the trees great apes typically travel using suspensory locomotion. They on rely their long forelimbs to move below the branches. The relatively short olecranon (short relative to the length of the ulnar shaft) provides a short force arm. A short force arm (relative to a long resistance arm) promotes speed. 9. Which primate species is in the comparison is capable of delivering the most power to its forearm during extension? Eulemur macaco or Saguinius fuscicollis 10. Why does Dasypus have such an extraordinary OU index? Explain in functional terms.
Armadillos are diggers to effectively move heavy dirt they need to generate considerable power during extension at the elbow. Their long olecranon indicates that the lever system of the triceps muscle and ulnar bone strongly favors power over speed. STATION III: LEVER SYSTEMS 1. Draw an example of each of different types of lever systems (they do not have to be biomechanical, just a simple drawing will do). Make sure and label each type of system. Additionally, label the system that is always built for power and then label the system that is always built for speed.
Station 3: Diet and Anatomy Incisal Row Length mm (I) SPECIES
Postcanine Row Length mm (P)
Ratio of incisors to postcanine teeth (I/P * 100) IP Index = 30.9
Alouatta palliata Howler Monkey
12.2mm
39.4mm
Cebus apella Capuchin
11.5mm
26.6mm
IP Index = 43.2
1. A) What does the IP ratio of incisors to postcanine teeth tell you about the diet of Alouatta? The IP ratio of Alouatta is lower than that of Cebus, suggesting that Alouatta has a higher component of leaves in its diet than does Cebus. B) How did you arrive at this conclusion? The ratio of Alouatta is low as a result of its narrow incisors. The prediction that Alouatta is folivorous is strongly supported by the presence of relatively narrow incisors. Reduced incisors indicate that the animal does very little if any incisal preparation of its food, as is characteristic of leaf ingestion the leaves go directly to the molars for shearing. 2. A) What does the ratio of incisors to postcanine teeth tell you about the diet of Cebus? In contrast, the IP ratio of Cebus is higher than that of Alouatta, suggesting that Cebus has a higher component of fruit in its diet than does Alouatta. B) How did you arrive at this conclusion? The IP ratio of Cebus is high as a result of its broad incisors. The prediction that Cebus is frugivorous is strongly supported by the presence of relatively large incisors. Broad incisors indicate that the animal performs incisal preparation of its food, as is characteristic of fruit ingestion. Fruits that are larger in overall size than the mouth of the consuming primate must be eaten in bites rather than ingested whole. Broad incisors are an advantage for biting off pieces of fruit that are then transferred to the molars for mashing or grinding. If a fruit is covered in a thick rind then broad incisors are additionally useful in separating the rind from the desired fruity interior. The same incisal preparation may be used when eating nuts with tough hulls.
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