A test for evolutionary equilibria: Phanerozoic brachiopods and Cenozoic mammals

Paleobiology ◽  
1977 ◽  
Vol 3 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Graham A. Mark ◽  
Karl W. Flessa
Keyword(s):  
Fossil Record ◽  
New World ◽  
Late Cenozoic ◽  
Equilibrium Models ◽  
Geographic Scale ◽  
Taxonomic Level ◽  
Temporal Intervals ◽  
Cenozoic Mammals

The fossil record of Phanerozoic brachiopod genera and Late Cenozoic New World mammal genera is examined for evidence of evolutionary equilibria. One necessary (but insufficient) condition is met: within temporal intervals, numbers of originations correlate with numbers of extinctions. Eliminating temporally short-ranging brachiopods, however, reduces the correlation so that it explains only 16% of the variation. More decisive tests of the equilibrium hypothesis appear impossible with available data. Difficulties of temporal and geographic scale, taxonomic level, and ecological consistency must be resolved before equilibrium models can be applied in paleontology for other than inspiration.

Precambrian metazoans: the problems of preservation, systematics and evolution

1985 ◽  
Vol 311 (1148) ◽  
pp. 27-45 ◽  
Keyword(s):  
Fossil Record ◽  
Ecological Factors ◽  
Metazoan Evolution ◽  
Taxonomic Level ◽  
Important Stage ◽  
New Information ◽  
Theoretical Predictions ◽  
Peculiar Nature ◽  
Phylogenetic Models

The unique appearance of Vendian metazoans in the Precambrian fossil record is controlled not only by taphonomic and ecological factors, but also by the level of morphological and physiological organization of these animals. The peculiar nature of these factors means that the Vendian represents an important stage in metazoan evolution. This notion is supported by the Bauplan analysis of Vendian forms, many of which have a bodyplan (architectonics) that is most unusual in comparison with animals from later periods. This new information allows a revision of the systematics of Precambrian metazoans at a high taxonomic level. The new classes Cyclozoa, Inordozoa, and Trilobozoa are recognized among Vendian Coelenterata. The phylum Proarticulata, with classes Dipleurozoa and Vendiamorpha, represents the most primitive Vendian Bilateria. These, the oldest faunas on Earth, provide indication of the earliest modes of metazoan evolution that have not been part of the theoretical predictions of neontologists, and they also serve as a tool to check certain phylogenetic models.

scholarly journals A new Late Cretaceous iguanomorph from North America and the origin of New World Pleurodonta (Squamata, Iguania)

2017 ◽  
Vol 284 (1847) ◽  
pp. 20161902 ◽  
Author(s):  
David G. DeMar ◽  
Jack L. Conrad ◽  
Jason J. Head ◽  
David J. Varricchio ◽  
Gregory P. Wilson
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
New World ◽  
Cladistic Analysis ◽  
Arid Environment ◽  
New Taxon ◽  
Low Latitude ◽  
Anatomical Features ◽  
Parietal Foramen

Iguanomorpha (stem + crown Iguania) is a diverse squamate clade with members that predominate many modern American lizard ecosystems. However, the temporal and palaeobiogeographic origins of its constituent crown clades (e.g. Pleurodonta (basilisks, iguanas, and their relatives)) are poorly constrained, mainly due to a meagre Mesozoic-age fossil record. Here, we report on two nearly complete skeletons from the Late Cretaceous (Campanian) of North America that represent a new and relatively large-bodied and possibly herbivorous iguanomorph that inhabited a semi-arid environment. The new taxon exhibits a mosaic of anatomical features traditionally used in diagnosing Iguania and non-iguanian squamates (i.e. Scleroglossa; e.g. parietal foramen at the frontoparietal suture, astragalocalcaneal notch in the tibia, respectively). Our cladistic analysis of Squamata revealed a phylogenetic link between Campanian-age North American and East Asian stem iguanomorphs (i.e. the new taxon + Temujiniidae). These results and our evaluation of the squamate fossil record suggest that crown pleurodontans were restricted to the low-latitude Neotropics prior to their early Palaeogene first appearances in the mid-latitudes of North America.

scholarly journals Rare dental trait provides morphological evidence of archaic introgression in Asian fossil record

2019 ◽  
Vol 116 (30) ◽  
pp. 14806-14807 ◽  
Author(s):  
Shara E. Bailey ◽  
Jean-Jacques Hublin ◽  
Susan C. Antón
Keyword(s):  
Fossil Record ◽  
New World ◽  
Homo Sapiens ◽  
Morphological Evidence ◽  
Compelling Evidence ◽  
Second Molar ◽  
Strong Link ◽  
Archaic Introgression ◽  
Fossil Hominin ◽  
Lower Molar

The recently described Denisovan hemimandible from Xiahe, China [F. Chen et al., (2019) Nature 569, 409–412], possesses an unusual dental feature: a 3-rooted lower second molar. A survey of the clinical and bioarchaeological literature demonstrates that the 3-rooted lower molar is rare (less than 3.5% occurrence) in non-Asian Homo sapiens. In contrast, its presence in Asian-derived populations can exceed 40% in China and the New World. It has long been thought that the prevalence of 3-rooted lower molars in Asia is a relatively late acquisition occurring well after the origin and dispersal of H. sapiens. However, the presence of a 3-rooted lower second molar in this 160,000-y-old fossil hominin suggests greater antiquity for the trait. Importantly, it also provides morphological evidence of a strong link between archaic and recent Asian H. sapiens populations. This link provides compelling evidence that modern Asian lineages acquired the 3-rooted lower molar via introgression from Denisovans.

Monitoriella Hedqvist (Hymenoptera: Braconidae: Doryctinae) from Brazil, with descriptions of three new species

Zootaxa ◽  
2011 ◽  
Vol 2921 (1) ◽  
pp. 28 ◽  
Author(s):  
EDUARDO MITIO SHIMBORI ◽  
ANGÉLICA MARIA PENTEADO-DIAS ◽  
JULIANO FIORELINI NUNES
Keyword(s):  
New Species ◽  
Atlantic Forest ◽  
New World ◽  
Brazilian Atlantic Forest ◽  
Taxonomic Level ◽  
Three New Species ◽  
Gall Inducer

Monitoriella Hedqvist is a phytophagous, gall-inducer Braconidae genus, known only from the New World. Its placement in a higher taxonomic level has been uncertain until recent phylogenetic investigations on cyclostome braconids, which reinforce its position in Doryctinae. Three new species of Monitoriella are described: M. costalimai sp. nov., M. spinata sp. nov., and M. ubatuba sp. nov., all from the Brazilian Atlantic Forest. Monitoriella anthurii is redescribed and illustrated. A key to all known species is provided.

Late Cenozoic mammals from central Mexico

1984 ◽  
Vol 4 (2) ◽  
pp. 216-236 ◽  
Author(s):  
Wade E. Miller ◽  
Oscar Carranza-Castañeda
Keyword(s):  
Central Mexico ◽  
Late Cenozoic ◽  
Cenozoic Mammals
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