Mark McMenamin

Mark McMenamin
Mount Holyoke College | MHC · Department of Geology

PhD, Geology

About

153
Publications
60,077
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1,410
Citations
Citations since 2016
53 Research Items
469 Citations
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Mark McMenamin is geosciences researcher and geology professor at Mount Holyoke College. His main research interests are paleontology and geology, particularly as these involve the origin and distribution of complex life forms. His best-known contribution is the discovery of the Clemente Formation's Ediacaran biota in Sonora, México.
Additional affiliations
July 1984 - present
July 1984 - June 2016
Mount Holyoke College
Position
  • Professor of Geology, Mount Holyoke College
July 1984 - February 2017
Mount Holyoke College
Position
  • Professor of Geology
Education
September 1979 - June 1984
September 1976 - May 1979
Stanford University
Field of study
  • Geology

Publications

Publications (153)
Article
The discovery of the network trace fossil Multina isp. in the Luning Formation of central Nevada provides new insight into the depositional setting of the Shaly Limestone Member of the Luning Formation. The ichnofossils occur in tabular mudstone beds deposited on a shelf environment or open carbonate platform. Although Multina resembles Paleodictyo...
Book
Using a series of case studies, the book demonstrates the power of dynamic analysis as applied to the fossil record. Written in an engaging and informative style, Dynamic Paleontology outlines the best application of quantitative and other tools to critical problems in the paleontological sciences such as analysis of the the Cambrian Explosion and...
Article
Full-text available
In this review, Mark McMenamin critiques Erwin and Valentine's book The Cambrian Explosion as failing to grasp the full implications of the singularity of the Cambrian event. McMenamin also revises the phylogenetic placement of both Eoandromeda (it is a vendobiont Ediacaran, not a ctenophore) and Cotyledion tyloides (it is an echinoderm, not an ent...
Article
The land ecosystem, in spite of its relative youth, outstrips the marine ecosystem in terms of greater primary productivity and species diversity per unit area. This occurs because land eukaryotes actively direct the flow of nutrient-rich fluids. The body fluids of land eukaryotes have had a significant evolutionary and geochemical impact, and we h...
Article
Full-text available
Lower Cambrian strata (Weisner-Shady Formations) of the Sleeping Giants Ridge Complex in eastern Alabama have produced archaeocyaths not previously reported from the southern Appalachians. The unusual, thorny-archaeocyath Yukonensis sp. is reported here and represents the first find of the genus outside of Yukon Territory and Alaska. An Early Cambr...
Article
Full-text available
Silicified ostracods from the Tin Mountain Limestone provide new information regarding the Carboniferous paleontology of the Death Valley Region, California, USA. Acid maceration of marine limestones yielded the following ostracods: Acratia spp., Bairdia quasilecta, Bairdia sp. cf. B. orientalis, Ceratobairdia sp., Kirkbya panamintensis sp. nov., R...
Article
Full-text available
Arkosic sandstone and lacustrine shale of Early Jurassic age from South Hadley, Massachusetts, has yielded articulated wing bones and a tooth belonging to a non-pterodactyloid pterosaur. The articulated bone material, imaged here by means of microCT scan, is almost entirely embedded in arkosic sandstone matrix. The presence of a pteroid confirms th...
Article
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Dinosaur bone material is rare in the Portland Formation of the Hartford Basin (Newark Supergroup) of western Massachusetts, although dinosaur tracks are abundant in the Portland. The distal epiphysis and metaphysis of a humerus belonging to a large neotheropod is described here from Amherst, Massachusetts. Analysis of the fossil shows that large (...
Article
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Bradoriids, among the earliest arthropods to appear in the fossil record, are extinct, ostracod-like bivalved forms that ranged from the early Cambrian to the Middle Ordovician. Bradoriids are notable for having appeared in the Cambrian fossil record before the earliest trilobites, and considering their rapid ascent to high genus-level diversity, p...
Preprint
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Analysis of plesiosaur swim dynamics by means of a digital 3D armature (wireframe “skeleton”) of a pliosauromorph (“Ava”) demonstrates that: 1, plesiosaurs used all four flippers for primary propulsion; 2, plesiosaurs utilized all four flippers simultaneously; 3, respective pairs of flippers of Plesiosauridae, front and rear, traveled through disti...
Preprint
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We report here a giant microfossil resembling the conidium of an ascomycete fungus (cf. Alternaria alternata). The specimen is preserved in stromatolitic black chert of the Gunflint Iron Formation (Paleoproterozoic Eon, Orosirian Period, ca. 1.9-2.0 Ga) of southern Ontario, Canada, and the rock that provided the thin section may have been collected...
Article
Full-text available
The Hypertopia Option, described here, uses the inherent connectivity of the land biota to combat the anthropogenic accumulation of carbon dioxide in the atmosphere. The crux of the proposal is that we must soon establish new towns (Hypertopias) in arid and marginal land areas, with inhabitants hand-nurturing nascent forests until these are suffic...
Article
Full-text available
Deuterostomes make a sudden appearance in the fossil record during the early Cambrian. Two bilaterian groups, the chordates and the vetulicolians, are of particular interest for understanding early deuterostome evolution, and the main objective of this review is to examine the Cambrian diversity of these two deuterostome groups. The subject is of p...
Preprint
We report here a ‘giant microfossil’ resembling the conidium of an ascomycete fungus (cf. Alternaria alternata). The specimen is preserved in stromatolitic black chert of the Gunflint Iron Formation (Paleoproterozoic Eon, Orosirian Period, ca. 1.9-2.0 Ga) of southern Ontario, Canada, and the rock that provided the thin section may have been collect...
Preprint
Eight amniote genera (representing four clades) became aquatic during the Permian. The four clades were mesosaurids, tangasaurids, the neodiapsid Claudiosaurus, and the procolophonid Barasaurus. Two of eight genera survived the end-Permian mass extinction, but did not last long into the Mesozoic. A previously undescribed specimen of Claudiosaurus g...
Preprint
Full-text available
Eight amniote genera (representing four clades) became aquatic during the Permian. The four clades were mesosaurids, tangasaurids, the neodiapsid Claudiosaurus, and the procolophonid Barasaurus. Two of eight genera survived the end-Permian mass extinction, but did not last long into the Mesozoic. A previously undescribed specimen of Claudiosaurus g...
Preprint
Full-text available
Deuterostomes make a sudden appearance in the fossil record during the Early Cambrian. Two deuterostome groups, the chordates and the vetulicolians, are of particular interest for understanding the evolutionary dynamics of the Cambrian evolutionary event. Lagerstätten in China and elsewhere have dramatically improved our understanding of the range...
Conference Paper
Full-text available
An undescribed new species of vetulicolian (Vetulicolian n. sp.) from the Early Cambrian Chengjiang Biota (Burgess Shale-Type (BST) deposit; Maotianshan Shale, 518 Ma) represents the earliest example of ‘angelfish’ body form in a nectobenthic deuterostome. The preserved length of the animal is 5 cm, with an anterior body region 4 cm deep. Sagittal...
Chapter
The primary feathers on the hind limbs of Microraptor give us an important clue about the nature of the ‘feather scleritome’. The Microraptor morphogenetic field hosts four curved projections representing the animal’s limbs. This is the case for all tetrapods. Like the bot fly larva, but in reverse, the extra sclerites/enations (maggot spines versu...
Chapter
A vestigial second dorsal fin spine in a Carboniferous rhabdodermatid coelacanth (cf. Rhabdoderma sp.) provides new data bearing on the evolutionary origins of coelacanths. The fossil was recovered from a cannel coal deposit in the Allegheny Group of Ohio. A vestigial second dorsal fin spine occurs between the second dorsal fin endochondrial suppor...
Chapter
The Shuram excursion represents the greatest negative carbon isotopic excursion in earth history, and provides an important chemostratigraphic marker horizon of global extent. The excursion is linked to the second great oxygenation event in earth history, an oxygen crisis that resulted in a transition from sulfidic oceans to a marine realm rich in...
Chapter
The ichnofossils Treptichnus and Multina provide clues about the development of behavior in burrowing metazoans. A particular behavior type may be condensed and superimposed on the original burrowing pattern of programmed behavior. For example, a fine scale sinusoidal pattern may be superimposed on a large scale sinusoidal pattern. Side to side sma...
Chapter
A small stemmed projectile point from western Massachusetts possibly dating to the Late Woodland Phase (1100–300 years ago) but of unknown age (but in any case less than about 18,000 years old), was fabricated from a locally available crystal of orthoclase feldspar derived from granite or granodiorite. Fabrication of the point demonstrates a fairly...
Chapter
The date of arrival of humans in the Americas is a long-standing puzzle in archaeology. A vein quartz biface from southern New England (South Hadley, Massachusetts) represents the oldest evidence for human occupation in New England, one of the last places in the United States to be colonized by Homo sapiens. The biface, which was resharpened and re...
Chapter
The enigmatic Middle Devonian chordate Palaeospondylus gunni from the the Achannaras Slate Quarry, Caithness, Scotland, has recently been reinterpreted as a member of the Cyclostomata (the group that includes living jawless fishes). If this interpretation is correct, then Palaeospondylus either retains a vertebral column as a vestigial organ, or re...
Chapter
The seven laws of morphogenetic evolution allow us to better comprehend the constraints and possibilities of evolutionary change. Parity bits of Hamming’s error-correcting code procedure may be used to simulate the appearance and disappearance of the scleritome. The Seventh Law states that morphogenetic field vectors may be bundled or dilated in a...
Chapter
New specimens of the procolophonoid parareptile Barasaurus from the Permo-Triassic Sakamena Group of Madagascar show skin preservation in the form of scale patches. Based on its appendicular skeletal anatomy, Barasaurus was an aquatic form, the only known aquatic procolophonoid. Its squamation consisting of large (up to 4 mm greatest dimension on a...
Chapter
Marsupials first appear in Cretaceous North America, their ancestors having arrived from Asia during an eastward migration of Mesozoic metatherians. By the end of the Mesozoic, the North American metatherians had developed into large (over one meter long) animals with a powerful bite force, partly a function of hypertrophied premolars (p3) in some...
Chapter
An agglutinated animal (or possibly protist) of the Late Proterozoic Clemente Formation biota cemented an array of tourmaline crystals (trigonal prisms; schorl/dravite composition) to its dorsal surface, presumably as ballast, in the earliest known case of an agglutinated animal. Quantitative confirmation of the spatial association (clustering) of...
Chapter
A diverse fauna of Ediacarans from the Clemente Formation of northwestern Sonora, México, includes Pteridinium cf. P. simplex, a recumbent sand frond Beothukis cf. B. mistakensis, the kimberellomorph Kimberella cf. K. quadrata, the solzid kimberellomorph Zirabagtaria ovata n. gen. n. sp., the praecambridiid Palankiras palmeri n. gen. n. sp., Vendam...
Article
Full-text available
We present a plausible account of the origin of the archetypal vertebrate bauplan. We offer a theoretical reconstruction of the geometrically regular structure of the blastula resulting from the sequential subdivision of the egg, followed by mechanical deformations of the blastula in subsequent stages of gastrulation. We suggest that the formation...
Chapter
What controls the geometry of the scleritome mosaic? Does it have any relationship to the rapid, major morphological changes? Morphogenetic field analysis helps to explain, by means of laws of morphogenetic evolution , the geometrical patterning of sclerites in a scleritome. Many cases of convergent evolution may thus be viewed as torologous relati...
Chapter
Analysis of the feeding strategy of the bizarre fossil Retilamina shows that this archaeocyath represents the earliest known example of animal mixotrophy in Earth history. Retilamina is estimated here to have been approximately 80 % photoautotrophic and 20 % heterotrophic.
Chapter
Why do characteristic features of the Proterozoic sea floor reappear in Mesozoic lake strata? The reappearance is a case of environmental convergence, where very similar environmental/ecological settings appear at widely separated moments in geological time. In this and other cases, non symmetry in the fossilized biofilms is key to recognition of a...
Chapter
What factors influence the postmortem alignment of conical shells? The Hyolith Effect defined here states that if we push any shape parameter subjected to stream flow (actual or metaphorical) beyond a particular threshold, we can expect dramatic system reorientations.
Chapter
What causes the unique shape of the Christmas tree stromatolite Jacutophyton? Branching in Jacutophyton appears to be controlled by both shade avoidance and by metazoan perturbation of the microbial mat at the edge of the stromatolite. Evidence suggests that heliotrophism in Proterozoic stromatolites is a real phenomenon.
Chapter
What role did agnostid trilobites play in the Cambrian ecosystem? Agnostids were predatory, and were capable of killing smaller members of their own species. Genocide and cannibalism can be traced back to the Early Cambrian, as can cooperative behavior such as group migration. It is plausible to predict that eusociality (at least in its rudimentary...
Chapter
What killed the giant ichthyosaurs of Berlin-Ichthyosaur State Park in Nevada? The leading hypothesis is that a giant octopus-like cephalopod attacked and killed the Shonisaurus ichthyosaurs and dragged their corpses to the Triassic sea floor. The Triassic Kraken hypothesis has survived all tests to date, and currently stands alone as the best expl...
Chapter
Why does the Proterozoic shelly fossil Qinella occur in a Cambrian limestone? Qinella’s unique shell morphology, thin walls separated by fluid–filled spaces (etch stop defense), served as an effective deterrent to Cambrian shell–boring predators. Family Cloudinidae was likely driven to extinction by first boring, and later crushing, predators. Qine...
Chapter
How abrupt was the Cambrian Explosion? Analysis of the Lignor-Sipps effect indicates that the burst of new phyla at the Cambrian Explosion was more real than apparent. The reason (or reasons) for this Big Bang of macroevolution remains unexplained.
Chapter
What did the giant Shonisaurus ichthyosaurs eat? Analysis of their coprolites indicates that shonisaurs fed on coelacanths, a fish type that is often associated with deeper water habitats. It is possible to make comparisons between Triassic and modern deep water, open ocean communities. Environmental convergence may be measured in tetrapod:cephalop...
Chapter
When did the first fruits appear? The ‘fruit grade’ of plant evolution was apparently attained by multiple lineages (Caytoniales, angiosperm ancestors) simultaneously in the earliest Jurassic at a time of profound global cooling in the wake of a major mass extinction. Where fossils are rare, due to their enclosing strata being deposited shortly aft...
Chapter
When did nesting behavior and advanced care of young first appear? The microburrow nests of archaeocyathan reef crypt spaces provide the first evidence for: 1, advanced metazoan behavioral complexity, 2, maternal care, 3, nesting behavior, 4, nest site fidelity, 5, evidence for rudimentary eusociality, and 6, evidence for animalian internal fertili...
Chapter
What caused the Cambrian Explosion? The geologically simultaneous appearance of numerous animal phyla at the base of the Cambrian was caused by an epidemic of Cambrian Explosion (CE) virus, a “phylagen” (as opposed to pathogen) that was able to infect and reconfigure metazoan morphogenetic fields and genomic kernels. The morphological change in eac...
Chapter
How old are the oldest animal trace fossils, and what size did they attain? Several candidate occurrences have been described. Vermiforma antiqua, Plexus ricei and the Trezona Formation structures are very ancient Proterozoic trace fossils. Plexus ricei occupied a now extinct ‘mat–cutter’ niche. The oldest biomat–associated ichnofossils occur in th...
Article
M. A. S. McMenamin and colleagues described a unique crustacean fossil from the Triassic Luning Formation in west-central Nevada as a new genus and species of amphipod, Rosagammarus minichiellus McMenamin, Zapata and Hussey, 2013. The amphipod identity caused an over-150-million-year ghost range connecting R. minichiellus with the next-oldest fossi...
Conference Paper
An unusual ichthyosaur skeleton ( Ichthyosaurus cf. I. breviceps Owen, 1881), collected from Holzmaden strata (Schomberg Quarry) some time before 1975 and currently in the collection of P. Reiter, shows evidence for trauma that involved breaking the neck by twisting the skull, leaving it 180° out of place while maintaining its orientation in line w...
Article
Full-text available
This article discusses the writings of Pierre Teilhard de Chardin SJ, and indicates the perils of using incorrect or tentative scientific results when proposing a theological worldview.
Book
Full-text available
This book represents Matt Lafreniere's student internship project for Holyoke Catholic High School, undertaken with Professor Mark McMenamin at Mount Holyoke College in summer 2012. The subject matter lends itself to both K-12 education and to scientifically fruitful consideration of a wide variety of ancient organisms. It may truly be said that a...
Book
Full-text available
In addition to the traditional four classes of tetrapods, amphibians (Class Amphibia), reptiles (Class Reptilia), birds (Class Aves) and mammals (Class Mammalia), herein is introduced a new, fifth class of tetrapods—Class Paramphibia. Paramphibians are characterized by a unique morphogenetic field with field lines that diverge and converge in alter...
Book
Full-text available
An archaic human mandible ("Penghu Man" or Penghu 1, here named Homo tsaichangensis n. sp.) dredged from the Penghu Channel off the west coast of Taiwan shows intriguing similarities to a newly reported jaw fragment from Tegal, central Java, here assigned to Gigantopithecus cf. G. blacki. These Pleistocene creatures may have inhabited similar envir...
Article
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This exchange of letters, written in reply to Mark McMenamin's cover story in the previous issue of New Oxford Review, discusses the significance and interpretation of the work of Pierre Teilhard de Chardin and Harvard anatomist Thomas Dwight.
Article
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This paper reports the discovery of a geometrical algorithm that provides a coherent step by step mechanical account of the structure of the nervous system, including the vertebrate brain, the spinal cord, the vertebral column, and the spinal nerves. The morphology of these organs and the observed steps of neural development are well described, con...
Conference Paper
Full-text available
The Signor-Lipps Effect explains the tendency of mass extinctions to appear gradual due to differential preservation among organisms of various sizes and abundances. Signor‑Lipps also applies to estimates of the origination dates of taxa appearing as fossils long after their actual first appearances. Swapping extinction for origination when conside...
Article
The fossil giant amphipod Rosagammarus minichiellus n. gen., n. sp. occurs in Triassic limestone (Luning Formation, west-central Nevada) in association with giant ichthyosaurs (Shonisaurus sp.) and the deep-water trace fossil Protopaleodictyon ichnosp. Fossil pereion and pereiopod morphology suggest affinities with the Acanthogammaridae, a freshwat...
Chapter
Full-text available
The Proterozoic (2.5 Ga–545 Ma) is perhaps the most intriguing period in Earth’s history. In a typical high school physical science textbook it may be presented as a rather boring period that today’s student is happy to pass over in lieu of the Mesozoic and the extinction of Tyrannosaurus rex by a large asteroid. In reality this was a period full o...
Conference Paper
Full-text available
In 2011, we hypothesized that extremely large Triassic cephalopods may be responsible for certain anomalous aspects of an unusual assemblage of giant ichthyosaur skeletons in the Luning Formation of Nevada. The hypothesis has been criticized by researchers who do not accept the ichnological evidence suggesting that the skeletons were deliberately a...
Conference Paper
Full-text available
The small shelly fossil Qinella occurs in an oolite sample from the Lower Cambrian Wood Canyon Formation, Echo Canyon, Death Valley, California. Until now, Qinella has been reported exclusively from upper Proterozoic strata. The Death Valley specimens reach 3.5 mm diameter, and are preserved in limestone matrix that hosts ooids, trilobites, and arc...
Article
Full-text available
Largely due to their diminutive size, agnostid trilobites have defied attempts to properly interpret their affinities, environmental preferences, ethology, and feeding strategies. Results from a suite of 44 separate slabs bearing specimens of Peronopsis interstricta provide new data concerning agnostid behavior. All samples were obtained from the M...
Article
Full-text available
An unusual arrangement of ichthyosaur bones in central Nevada has perplexed paleontologists for decades. Originally thought to be a site of mass stranding in shallow water, more recent research results indicate that it represents a deep-water site. This paper reviews the geological and statistical evidence favoring the Triassic Kraken hypothesis, n...
Article
Full-text available
MITOCHONDRIA IN YEAST CELL Margulis viewed mitochondria, which generate the energy for cell metabolism, as descended from free-roaming parasitoid bacteria. Here, an electron micrograph of a yeast cell, showing mitochondria (small black bodies). The arrow points to a mitochondrion that is apparently dividing. EXAMPLE OF A PROTOCTIST, WHICH EVOLVED F...
Conference Paper
Full-text available
Enigmatic Early Cambrian limestone cavities filled with homogenous matrix and penetrated by microburrows occur in archaeocyathan carbonates of Mexico (northwestern Sonora) and Nevada (Barrel Springs). Matrix was formed by closely packed pellets 0.25-0.5 mm in diameter. Pellets disaggregated to form lime mud penetrated by microburrows. The microburr...
Article
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Acid maceration and thin section analysis of archaeocyathan limestones of the Cerro Clemente and Cerro Rajón, Sonora, México, have yielded some of the most ancient sponge fossils reported from the North Ameri-can Cordillera. The sponge fossils are from Unit 3 of the Puerto Blanco Formation. The fossils include one of the earliest known specimens of...
Article
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The Carolina Terrane has yielded very few Ediacaran-age fossils. These included Pteridinium carolinaensis, cf. ?Swartpuntia sp. and a variety of trace fossils. Recent col-lecting efforts in the Albemarle Group have yielded Sekwia excentrica from the Floyd Church Formation, an indeterminate sac-like organism from the unnamed Mudstone Member of the C...
Article
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Evidence internal to the document indicates that the Gospel of John is based on an eyewitness account.
Article
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The image on a Greek coin of the second-first century BC is identified as an ammonite fossil and linked to the eponymous Ammon, the Egyptian ram-headed god.
Article
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New partial swartpuntiid from Neoproterozoic age rocks of Stanly County, North Carolina, herein assigned to cf. ?Swartpuntia sp., along with previously described Pteridinium carolinaensis, Aspidella, other metazoan trace fossils, and previously reported radiometeric ages, suggest Nama Assemblage type affinities for the Carolina Terrane. The new spe...
Chapter
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Time normalized analyses of the feeding strategies of marine metazoan families which both originated and terminated during the Cenomanian and Maastrichtian shows that more primary consumers suffered extinction in the Maastrichtian than in the Cenomanian. Each family was assigned a percentile “trophic score ”based on the feeding strategies that they...
Conference Paper
Full-text available
In a series of two lectures at the 24th Cosmos and Creation annual conference at Loyola College in Baltimore, Maryland, Mark McMenamin showed that proper critique and criticism of Teilhard's legacy is essential for accurate assessment of Teilhard's contributions in both science (mostly positive) and theology (mostly disastrous).
Article
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Ptilophyllum was a cosmopolitan element of the Triassic-Jurassic cycadeoid flora. We describe here specimens of Ptilophyllum sp. from the Portland Formation in Granby, Massachusetts. This genus has not been reported before from strata of the Connecticut Valley. The discovery expands our knowledge of this region's floral diversity, environment, and...
Article
Full-text available
Cambrian polymeroid trilobites permit, for the first time, biostratigraphic correlation between the Carolina Slate Belt (Carolina terrane) and Belair Belt (Augusta terrane) of Georgia and North and South Carolina. An unnamed trilobite with an unusually wide thorax and an upturned anterior cranidial border (ptychoparioid genus and species A) allows...
Chapter
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The Lipalian or Vendian Period (600-541 million years ago) begins and ends with global environmental perturbations. It begins as the worst glaciation on record draws to a close. It ends with a sudden appearance of abundant skeletonized animals that mark the beginning of Cambrian ecology. Several key events in Earth history occur during the Lipalian...
Chapter
Full-text available
This chapter examines the influence of the biosphere on the initiation, and termination of, the glaciations of the late Proterozoic. Recent considerations suggest that the biosphere controlled the timing of the onset of glaciation and also controlled the timing of the end of glaciation. Massive carbonate accumulation and giant stromatolites of the...
Article
Full-text available
Our current knowledge on the origin and early evolution of large predators is summarized by Simon Conway Morris (1999, 153–154) as follows: ...for many years it was claimed that Cambrian marine communities were almost entirely free of predators… the seas were [thought to be] full of suspension-feeders gently swaying in the sea water and deposit fee...
Article
Full-text available
Pteridinium carolinaensis (St. Jean, 1973), once interpreted as a trilobite, was shown by Gibson and others (1984) to be an Ediacaran fossil. A specimen collected from North Carolina in 1986 has distinctive radiating tubular canals emanating from axial nodes. The position of these tubes or canals is considered here to be diagnostic for the species....
Article
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A specimen of a Middle Cambrian ptychoparioid trilobite with a complete thorax permits description of the new genus Skehanos gen. nov. Skehanos quadrangularis (Whitfield) occurs in Hayward's Quarry of the Braintree Slate in Quincy, Massachusetts. Skehanos quadrangularis also occurs in the Asbill Pond formation of South Carolina, as does the solenop...
Book
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Chapter
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This paper describes the fallotaspidoid trilobite Avefallotaspis maria gen. et sp. nov. and the olenellinid trilobite Sanctaspis avemaria gen. et. sp. nov., and discusses the rapid evolutionary exploration of morphospace by trilobites in the Early Cambrian.
Article
New data allow us to correlate the Early Cambrian archaeocyathan faunas of the Appalachian (eastern)and Cordilleran (western) faunal provinces of Laurentia. The precise relationships of fossil assemblages between these provinces have hitherto been controversial, with the correlation of the Elliptocephala asaphoides Fauna posing particular problems....
Conference Paper
Full-text available
McMenamin, M. A. S.. 2001. The Garden of Ediacara and the Appearance of Complex Life. Proceedings of the International School of Earth and Planetary Sciences, Earth System Science, Certosa di Potinganano, Siena 2001, p. 61-68. The bilaterally-symmetric Ediacaran Gehlingia and the triradially-symmetric Ediacaran Tribrachidium share homologous "thum...

Questions

Questions (39)
Question
Specifically, are there any cortical/compact bone tissue differences between dinosaurs and crocodilians.