Morphology‐based systematics (MBS) and problems with fossil hominoid and hominid systematics

Abstract

The generalized/primitive nature of the hominoid dentition and often fragmentary nature of fossils, coupled with enthusiastic optimism for making revolutionary finds, has wreaked havoc with recognition of early human ancestors and reconstruction of fossil hominoid phylogeny. As such, the history of paleoanthropology is one of repeated misidentification of fossil ancestors and of occasional fraud. Although this history has led many workers to lose confidence in morphology based systematics (MBS), past and present misidentifications are actually due to a disregard of systematic methodology. Systematics depends on the continuity of life and gains its objectivity largely from the order alpha taxonomy imposes on morphologic discontinuities in closely related taxa (i.e., species and genera). Transformation of characters fixed in species into character complexes, as manifested in taxa nested at different levels of relationship, form the foundation for higher-level taxonomy and for phylogeny. Because in most cases, hominoid fossils are unable to provide the data needed to resolve alpha taxonomy, classification and phylogeny of fossil taxa must be guided by analogies to living taxa. Hominid and hominoid fossil taxonomy and phylogeny, however, has been based largely on preevolutionary notions and on misinterpretations of the polarity of assumed diagnostic characters. More often than not, fossils lack resolution for the taxonomic level or rank they are assigned to and taxa are erected without appropriate analogies to living forms. As such, phylogenies based on these classifications are unlikely to be correct. More in-depth anatomical studies that are in accordance with systematic methodology are likely to hold the key to correctly classifying fossils and unraveling hominoid and hominid phylogeny. Anat Rec (New Anat) 269:50 -66, 2002.

The Primitive Wrist of Homo floresiensis and Its Implications for Hominin Evolution

“…E-mail: tocherim@si.edu carpal elements and in the configuration of the articular surfaces (8)(9)(10)(11)(12). In primates, the trapezoid is the wrist bone situated directly proximal to the index finger.…”

Comment on the Paleobiology and Classification of Ardipithecus ramidus

“…However, reliance on the canine/premolar complex to diagnose hominids (in the classic sense) has misdiagnosed Miocene fossil apes (i.e., Oreopithecus and Ramapithecus) as early human ancestors (12,13). Character polarity for this complex is not clear-cut, with many early hominoids, especially females, often showing a humanlike condition.…”

“…Character polarity for this complex is not clear-cut, with many early hominoids, especially females, often showing a humanlike condition. The canine/ premolar complex shows such a marked grade of character lability (e.g., conspecific males and females show the diagnostic character differences) that reversals in polarity could have occurred repeatedly over the evolutionary periods necessary for these fossil genera to differentiate (12). Approximation to the humanlike canine/premolar complex, therefore, does not indicate that Ardipithecus is a hominid or ancestral to Australopithecus any more than it indicates that Oreopithecus and the orangutan-like females of Sivapithecus, both of which also share a humanlike premolar/canine complex, are hominids or represent a descendantancestor continuum.…”

“…Nearly all are quantitative characters that appear in early hominoids (i.e., Oreopithecus and Dryopithecus) and have appeared independently in other primate lineages, and character simplicity is such that parallelisms or reversals in polarity cannot be demonstrated (12,15). Moreover, attempts to link Ar.…”

“…Even if Ar. ramidus was an exclusive member of the human, chimpanzee, or gorilla lineages, given its proximity in time to this divergence date, it would be difficult to unambiguously recognize it as such (12,27,28). It therefore seems premature to use Ar.…”