Phylogenetic Position and Morphology of Ramapithecus — 2019 Paper II

Approach

• Demand of Question: Explain the changing phylogenetic interpretation of Ramapithecus and describe its important morphological characteristics.
• Structuring the Response: Begin with discovery and earlier hominid status, then explain its revised position using later fossil and molecular evidence.
• Key Dimensions to Cover: G.E. Lewis, Siwaliks, Simons-Pilbeam, Sivapithecus, thick enamel, reduced canine and pongine affinity.

Model Answer

Introduction: Ramapithecus was described by G.E. Lewis in 1934 from Miocene deposits of the Siwalik Hills. Initially regarded as an important possible human ancestor, its phylogenetic position was later substantially revised.

Earlier position: Elwyn Simons and David Pilbeam considered Ramapithecus close to the hominid line because of:

• relatively reduced canines;
• thick molar enamel;
• robust jaws;
• apparently shortened dental arcade.

These features appeared more human-like than those of contemporary apes.

Revised position: Discovery of more complete fossils showed strong similarities with Sivapithecus. Molecular evidence also indicated a considerably later divergence of the human and African-ape lineages.

Thus:

Ramapithecus → Sivapithecus complex → Pongine lineage

It is now generally regarded as closely related to the orangutan lineage, rather than a direct human ancestor.

Morphological features:

• thick-enamelled cheek teeth;
• broad molars;
• relatively reduced canines;
• powerful masticatory apparatus;
• robust mandibular structure.

Conclusion: Ramapithecus illustrates how new fossil and molecular evidence can transform phylogenetic interpretation; today it is placed closer to Miocene Asian pongines than to hominins.