scholarly journals Hominin taxic diversity: Fact or fantasy?

2016 ◽  
Vol 159 ◽  
pp. 37-78 ◽  
Author(s):  
Bernard Wood ◽  
Eve K. Boyle
Keyword(s):  
Taxic Diversity

Anatomical, morphometric, and stratigraphic analyses of theropod biodiversity in the Upper Cretaceous (Campanian) Dinosaur Park Formation

2021 ◽  
pp. 1-15
Author(s):  
Thomas M. Cullen ◽  
Lindsay Zanno ◽  
Derek W. Larson ◽  
Erinn Todd ◽  
Philip J. Currie ◽  
...  
Keyword(s):  
High Resolution ◽  
North America ◽  
Fossil Record ◽  
Upper Cretaceous ◽  
Environmental Changes ◽  
Morphometric Analyses ◽  
Variable Distribution ◽  
Taxic Diversity ◽  
Dinosaur Park Formation ◽  
Broad Scale

The Dinosaur Park Formation (DPF) of Alberta, Canada, has produced one of the most diverse dinosaur faunas, with the record favouring large-bodied taxa, in terms of number and completeness of skeletons. Although small theropods are well documented in the assemblage, taxonomic assessments are frequently based on isolated, fragmentary skeletal elements. Here we reassess DPF theropod biodiversity using morphological comparisons, high-resolution biostratigraphy, and morphometric analyses, with a focus on specimens/taxa originally described from isolated material. In addition to clarifying taxic diversity, we test whether DPF theropods preserve faunal zonation/turnover patterns similar to those previously documented for megaherbivores. Frontal bones referred to a therizinosaur (cf. Erlikosaurus), representing among the only skeletal record of the group from the Campanian–Maastrichtian (83–66 Ma) fossil record of North America, plot most closely to troodontids in morphospace, distinct from non-DPF therizinosaurs, a placement supported by a suite of troodontid anatomical frontal characters. Postcranial material referred to cf. Erlikosaurus in North America is also reviewed and found most similar in morphology to caenagnathids, rather than therizinosaurs. Among troodontids, we document considerable morphospace and biostratigraphic overlap between Stenonychosaurus and the recently described Latenivenatrix, as well as a variable distribution of putatively autapomorphic characters, calling the validity of the latter taxon into question. Biostratigraphically, there are no broad-scale patterns of faunal zonation similar to those previously documented in ornithischians from the DPF, with many theropods ranging throughout much of the formation and overlapping extensively, possibly reflecting a lack of sensitivity to environmental changes, or other cryptic ecological or evolutionary factors.

scholarly journals New specimen of <i>Cacops woehri</i> indicates differences in the ontogenetic trajectories among cacopine dissorophids

Fossil Record ◽  
2015 ◽  
Vol 18 (1) ◽  
pp. 73-80 ◽  
Author(s):  
N. B. Fröbisch ◽  
A. Brar ◽  
R. R. Reisz
Keyword(s):  
Morphological Changes ◽  
Lower Permian ◽  
Ecological Diversity ◽  
Large Specimen ◽  
Skull Morphology ◽  
Skull Shape ◽  
Ontogenetic Trajectories ◽  
Ontogenetic Trajectory ◽  
Taxic Diversity

Abstract. The Lower Permian Dolese locality has produced numerous exquisitely preserved tetrapod fossils representing members of a lower Permian upland fauna. Therein, at least nine taxa of the clade Dissorophoidea, ranging in size from the large predaceous trematopid Acheloma to the miniaturized amphibamid Doleserpeton, highlight the great taxic and ecological diversity of this anamniote clade. Here we describe a large specimen of the dissorophid Cacops woehri, which was previously only known from the juvenile or subadult holotype skull. Another member of the genus Cacops present at the Dolese locality, Cacops morrisi, is also represented by specimens spanning juvenile, subadult, and adult stages, allowing for a comparison of morphological changes taking place in the late phases of the ontogenetic trajectory of cacopine dissorophids. The new find shows that, in contrast to C. morrisi and C. aspidephorus, C. woehri only undergoes relatively subtle changes in skull morphology in late ontogeny and retains the overall more gracile morphology into adult stages. This includes retention of the rather shallow skull shape as well as a pattern of sculpturing consisting of elongate ridges and grooves and a large occipital flange. This suggests somewhat different functional demands in C. woehri than in other known species of Cacops, possibly associated with a different ecology paralleling the great taxic diversity of dissorophoids at the Dolese locality.

Developmental biology and human evolution

2011 ◽  
Vol 1 (1) ◽  
pp. e2
Author(s):  
Jeffrey H. Schwartz
Keyword(s):  
Biological Sciences ◽  
Population Genetics ◽  
Evolutionary Biology ◽  
Molecular Change ◽  
Human Fossil ◽  
Evolutionary Studies ◽  
History Of ◽  
Modern Evolutionary Synthesis ◽  
Organismal Development ◽  
Taxic Diversity

The Evolutionary or Modern Evolutionary Synthesis (here identified as the Synthesis) has been portrayed as providing the foundation for uniting a supposed disarray of biological disciplines through the lens of Darwinism fused with population genetics. Rarely acknowledged is that the Synthesis’s success was also largely due to its architects’ effectiveness in submerging British and German attempts at a synthesis by uniting the biological sciences through shared evolutionary concerns. Dobzhansky and Mayr imposed their bias toward population genetics, population (as supposedly opposed to typological) thinking, and Morgan’s conception of specific genes for specific features (here abbreviated as genes for) on human evolutionary studies. Dobzhansky declared that culture buffered humans from the whims of selection. Mayr argued that as variable as humans are now, their extinct relatives were even more variable; thus the human fossil did not present taxic diversity and all known fossils could be assembled into a gradually changing lineage of time-successive species. When Washburn centralized these biases in the new physical anthropology the fate of paleoanthropology as a non-contributor to evolutionary theory was sealed. Molecular anthropology followed suit in embracing Zuckerkandl and Pauling’s assumption that molecular change was gradual and perhaps more importantly continual. Lost in translation was and still is an appreciation of organismal development. Here I will summarize the history of these ideas and their alternatives in order to demonstrate assumptions that still need to be addressed before human evolutionary studies can more fully participate in what is a paradigm shift-in-the-making in evolutionary biology.

scholarly journals Sporadic sampling, not climatic forcing, drives observed early hominin diversity

2018 ◽  
Vol 115 (19) ◽  
pp. 4891-4896 ◽  
Author(s):  
Simon J. Maxwell ◽  
Philip J. Hopley ◽  
Paul Upchurch ◽  
Christophe Soligo
Keyword(s):  
Fossil Record ◽  
Detailed Examination ◽  
Hominin Evolution ◽  
Rock Exposure ◽  
Early Hominin ◽  
Positive Correlations ◽  
Taxic Diversity ◽  
Diversity Estimates

The role of climate change in the origin and diversification of early hominins is hotly debated. Most accounts of early hominin evolution link observed fluctuations in species diversity to directional shifts in climate or periods of intense climatic instability. None of these hypotheses, however, have tested whether observed diversity patterns are distorted by variation in the quality of the hominin fossil record. Here, we present a detailed examination of early hominin diversity dynamics, including both taxic and phylogenetically corrected diversity estimates. Unlike past studies, we compare these estimates to sampling metrics for rock availability (hominin-, primate-, and mammal-bearing formations) and collection effort, to assess the geological and anthropogenic controls on the sampling of the early hominin fossil record. Taxic diversity, primate-bearing formations, and collection effort show strong positive correlations, demonstrating that observed patterns of early hominin taxic diversity can be explained by temporal heterogeneity in fossil sampling rather than genuine evolutionary processes. Peak taxic diversity at 1.9 million years ago (Ma) is a sampling artifact, reflecting merely maximal rock availability and collection effort. In contrast, phylogenetic diversity estimates imply peak diversity at 2.4 Ma and show little relation to sampling metrics. We find that apparent relationships between early hominin diversity and indicators of climatic instability are, in fact, driven largely by variation in suitable rock exposure and collection effort. Our results suggest that significant improvements in the quality of the fossil record are required before the role of climate in hominin evolution can be reliably determined.

scholarly journals Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131071 ◽  
Author(s):  
Marcello Ruta ◽  
Kenneth D. Angielczyk ◽  
Jörg Fröbisch ◽  
Michael J. Benton
Keyword(s):  
Mass Extinction ◽  
Phylogenetic Diversity ◽  
Mass Extinctions ◽  
Triassic Boundary ◽  
Morphological Disparity ◽  
Morphological Novelty ◽  
Adaptive Radiations ◽  
Permian Mass Extinction ◽  
Original Potential ◽  
Taxic Diversity

Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade's final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.

scholarly journals Giant Mesozoic coelacanths (Osteichthyes, Actinistia) reveal high body size disparity decoupled from taxic diversity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lionel Cavin ◽  
André Piuz ◽  
Christophe Ferrante ◽  
Guillaume Guinot
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Morphological Evolution ◽  
Small Species ◽  
High Body ◽  
Large Size ◽  
Living Fossils ◽  
Size Disparity ◽  
Speciation Rates ◽  
Taxic Diversity

AbstractThe positive correlation between speciation rates and morphological evolution expressed by body size is a macroevolutionary trait of vertebrates. Although taxic diversification and morphological evolution are slow in coelacanths, their fossil record indicates that large and small species coexisted, which calls into question the link between morphological and body size disparities. Here, we describe and reassess fossils of giant coelacanths. Two genera reached up to 5 m long, placing them among the ten largest bony fish that ever lived. The disparity in body size adjusted to taxic diversity is much greater in coelacanths than in ray-finned fishes. Previous studies have shown that rates of speciation and rates of morphological evolution are overall low in this group, and our results indicate that these parameters are decoupled from the disparity in body size in coelacanths. Genomic and physiological characteristics of the extant Latimeria may reflect how the extinct relatives grew to such a large size. These characteristics highlight new evolutionary traits specific to these “living fossils”.

scholarly journals Morphospace saturation in the stem-gnathostomes pteraspidiformes heterostracans: an early radiation of a ‘bottom’ heavy clade

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5249
Author(s):  
Marco Romano ◽  
Robert Sansom ◽  
Emma Randle
Keyword(s):  
Evolutionary History ◽  
Late Devonian ◽  
Gradual Decline ◽  
Early Devonian ◽  
Morphological Disparity ◽  
Anatomical Features ◽  
Early Radiation ◽  
Taxic Diversity ◽  
Shed Light ◽  
Over Time

Ostracoderms (fossil armoured jawless fishes) shed light on early vertebrate evolution by revealing the step-wise acquisition of jawed vertebrate characters, and were important constituents of Middle Palaeozoic vertebrate faunas. A wide variety of head shield shapes are observed within and between the ostracoderm groups, but the timing of these diversifications and the consistency between different measures of their morphospace are unclear. Here, we present the first disparity (explored morphospace) versus diversity (number of taxa) analysis of Pteraspidiformes heterostracans using continuous and discrete characters. Patterns of taxic diversity and morphological disparity are in accordance: they both show a rise to a peak in the Lochkovian followed by a gradual decline in the Middle-Late Devonian. Patterns are largely consistent for disparity measures using sum of ranges or total variance, and when using continuous or discrete characters. Pteraspidiformes heterostracans can be classified as a “bottom-heavy clade”, i.e., a group where a high initial disparity decreasing over time is detected. In fact, the group explored morphospace early in its evolutionary history, with much of the subsequent variation in dermal armour occurring as variation in the proportions of already evolved anatomical features. This Early Devonian radiation is also in agreement with the paleobiogeographic distribution of the group, with a maximum of dispersal and explored morphospace during the Lochkovian and Pragian time bins.

Dobrogeria aegyssensis, a new early Spathian (Early Triassic) coelacanth from North Dobrogea (Romania)

2014 ◽  
Vol 64 (2) ◽  
pp. 161-187 ◽  
Author(s):  
Lionel Cavin ◽  
Eugen Grădinaru
Keyword(s):  
Lower Triassic ◽  
Early Triassic ◽  
New Taxon ◽  
Precise Description ◽  
Lower Jaw ◽  
Taxic Diversity ◽  
The City ◽  
Matrix Free ◽  
Single Living ◽  
Bone Remains

Abstract The Early Triassic witnessed the highest taxic diversity of coelacanths (or Actinistia), a clade with a single living genus today. This peak of diversity is accentuated here with the description of a new coelacanth discovered in the lower Spathian (Upper Olenekian, Lower Triassic) cropping out in the Tulcea Veche (Old Tulcea) promontory, in the city of Tulcea, in North Dobrogea, Romania. The bone remains were preserved in a block of limestone, which was chemically dissolved. The resulting 3D and matrix-free ossifications correspond mostly to elements of the skull and branchial apparatus. Posterior parietals, postparietal with associated prootic and basisphenoid allow a precise description of the neurocranium. Ossifications of the lower jaw, together with branchial and pectoral elements, complete the description of this coelacanth and support the coining of a new generic and specific name, Dobrogeria aegyssensis. A phylogenetic analysis of actinistians with the new species recovers clades which were found in most recent analyses, i.e. the Sasseniidae, the Laugiidae, the Coelacanthiformes, the Latimerioidei, the Mawsoniidae and the Latimeriidae, and identifies the new taxon as a non-latimerioid coelacanthiform.

scholarly journals A small caseid synapsid, Arisierpeton simplex gen. et sp. nov., from the early Permian of Oklahoma, with a discussion of synapsid diversity at the classic Richards Spur locality

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6615 ◽  
Author(s):  
Robert R. Reisz
Keyword(s):  
North America ◽  
Fossil Record ◽  
Middle Permian ◽  
Lower Permian ◽  
Early Permian ◽  
Faunal Assemblage ◽  
Lower Jaw ◽  
Continental Deposits ◽  
Faunal List ◽  
Taxic Diversity

The fossil record of caseids, a clade of faunivorous to large herbivorous Permian synapsids, is unusual in having a poorly documented history. Although Kungurian caseids are common in the well-known continental deposits of North America, and the fossil record of the group extends into the middle Permian (Guadalupian), with the presence of the large caseid Ennatosaurus in the Mezen Basin faunal assemblage, only two other occurrences are known in older Permian age sediments. One is an undescribed caseid from the Bromacker Quarry in Germany, and the second is Oromycter from the lower Permian of Richards Spur, Oklahoma. The former is known from several articulated skeletons, but the latter is known only from a handful of skeletal elements, including elements of the snout and lower jaw, some phalanges, and a few vertebrae. Here the fragmentary tooth bearing elements and dorsal vertebrae of another small caseid from Richards Spur are described, with a discussion of its significance in the context of caseid evolution, and the continuously expanding faunal list and taxic diversity at this locality.

scholarly journals Giant Mesozoic Coelacanths (Osteichthyes, Actinistia) Reveal High Body Size Disparity Decoupled From Taxic Diversity

2021 ◽  
Author(s):  
Lionel Cavin ◽  
André Piuz ◽  
Christophe Ferrante ◽  
Guillaume Guinot
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Morphological Evolution ◽  
High Rate ◽  
Small Species ◽  
Large Size ◽  
Living Fossils ◽  
Size Disparity ◽  
Speciation Rates ◽  
Taxic Diversity

Abstract The positive correlation between speciation rates and morphological evolution expressed by body size is a macroevolutionary trait of vertebrates. Although taxic diversification and morphological evolution are slow in coelacanths, their fossil record indicates that large and small species coexisted, which calls into question the link between morphological and body size disparities. Here, we describe and reassess fossils of giant coelacanths. Two genera reached up to 5 meters long, placing them among the ten largest bony fish that ever lived. The disparity in body size adjusted to taxic diversity is much greater in coelacanths than in ray-finned fishes, and is decoupled from a high rate of speciation or a high rate of morphological evolution. Genomic and physiological characteristics of the extant Latimeria may reflect how the extinct relatives grew to such a large size. These characteristics highlight new evolutionary traits specific to these “living fossils”.

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