Question

Which of the following species are included among gracile australopithecines?
A. A. africanus
B. A. boisei
C. A. afarensis
D. A. anamensis
Choose the correct answer from the options given below:

• A. A, B and D only
• B. A, B and C only
• C. A, C and D only
• D. B, C and D only

Hint:

Remember the key distinction: "gracile" means slender or lightly built, while "robust" means strong and heavily built. The robust species ({P. boisei}, {P. robustus}, {P. aethiopicus}) are specialized for heavy chewing and are often grouped into their own genus, {Paranthropus}.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The australopithecines are a group of extinct hominins. Paleoanthropologists classify them into two main morphological groups: "gracile" and "robust." This classification is based primarily on features related to chewing, such as the size of the teeth, jaws, and chewing muscles.
- Gracile australopithecines had a lighter build, especially in the skull and teeth. Their jaws were less massive, and their molars were smaller.
- Robust australopithecines (often placed in the genus Paranthropus) had massive jaws, enormous molars, and prominent sagittal crests on their skulls for the attachment of large chewing muscles.
Step 2: Detailed Explanation:
Let's classify each species:
- A. A. africanus: This is the classic example of a gracile australopithecine from South Africa.
- B. A. boisei: Also known as Paranthropus boisei, this species is the epitome of a "hyper-robust" australopithecine from East Africa, known for its massive jaws and molars. It is not gracile.
- C. A. afarensis: This East African species, famously represented by the "Lucy" fossil, is a gracile australopithecine.
- D. A. anamensis: This is one of the earliest australopithecine species and is considered a gracile form.
Step 3: Final Answer:
The species classified as gracile australopithecines are A. africanus, A. afarensis, and A. anamensis. A. boisei is a robust australopithecine. Therefore, the correct combination is A, C, and D only.