Investigating the effect of endocranial volume on cranial shape in platyrrhines and the relevance of this relationship to interpretations of the fossil record

2019 ◽  
Vol 169 (1) ◽  
pp. 12-30 ◽  
Author(s):  
Lauren Halenar‐Price ◽  
Melissa Tallman
Keyword(s):  
Fossil Record ◽  
Endocranial Volume ◽  
Cranial Shape

scholarly journals Pattern and process in hominin brain size evolution are scale-dependent

2018 ◽  
Vol 285 (1873) ◽  
pp. 20172738 ◽  
Author(s):  
Andrew Du ◽  
Andrew M. Zipkin ◽  
Kevin G. Hatala ◽  
Elizabeth Renner ◽  
Jennifer L. Baker ◽  
...  
Keyword(s):  
Fossil Record ◽  
Brain Size ◽  
Exponential Model ◽  
Human Fossil ◽  
Hominin Evolution ◽  
Size Evolution ◽  
Large Brain ◽  
Quantitative Basis ◽  
Endocranial Volume ◽  
Subsequent Disappearance

A large brain is a defining feature of modern humans, yet there is no consensus regarding the patterns, rates and processes involved in hominin brain size evolution. We use a reliable proxy for brain size in fossils, endocranial volume (ECV), to better understand how brain size evolved at both clade- and lineage-level scales. For the hominin clade overall, the dominant signal is consistent with a gradual increase in brain size. This gradual trend appears to have been generated primarily by processes operating within hypothesized lineages—64% or 88% depending on whether one uses a more or less speciose taxonomy, respectively. These processes were supplemented by the appearance in the fossil record of larger-brained Homo species and the subsequent disappearance of smaller-brained Australopithecus and Paranthropus taxa. When the estimated rate of within-lineage ECV increase is compared to an exponential model that operationalizes generation-scale evolutionary processes, it suggests that the observed data were the result of episodes of directional selection interspersed with periods of stasis and/or drift; all of this occurs on too fine a timescale to be resolved by the current human fossil record, thus producing apparent gradual trends within lineages. Our findings provide a quantitative basis for developing and testing scale-explicit hypotheses about the factors that led brain size to increase during hominin evolution.

Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

2012 ◽  
Vol 39 (2) ◽  
pp. 217-233 ◽  
Author(s):  
J. David Archibald
Keyword(s):  
Fossil Record ◽  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Charles Darwin ◽  
The Other ◽  
Charles Lyell ◽  
Single Origin ◽  
Molecular Studies ◽  
Richard Owen ◽  
First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

THE FIRST APPEARANCE OF CONTROLLED EUKARYOTIC BIOMINERALIZATION IN THE NEOPROTEROZOIC FOSSIL RECORD

2016 ◽  
Author(s):  
Phoebe Cohen ◽  
◽  
Justin V. Strauss ◽  
Alan D. Rooney ◽  
Mukul Sharma ◽  
...  
Keyword(s):  
Fossil Record

THE FOSSIL RECORD OF SQUAT LOBSTERS: FILLING IN THE GAPS

2016 ◽  
Author(s):  
Cristina M. Robins ◽  
◽  
Adiël A. Klompmaker
Keyword(s):  
Fossil Record ◽  
Squat Lobsters
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