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Gravity of the colony matched that of the surrounding seawater. Computer models and physical models, including exposure to wind-tunnel conditions that mimic the effects of water currents, have emphasized the importance of harvesting strategies for the success of the colony. These probably exerted an important influence on the evolutionary pathways that the grapto-loids followed. Evolution graptolite stipes and thecae Graptolite evolution has been described in terms of four main stages of...

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Ager Fossil

Figure 12.11 Lower Silurian depth-related paleocommunities developed across the Welsh and Anglo-Welsh region. (Based on Clarkson 1998.) Figure 12.12 Mesozoic palaeocommunities developed across Alpine Europe. Numbers 1 to 7 refer to the seven different biotypes described on the figure. (Based on Ager, D.V. 1965. Palaeogeogr. Palaeoclimatol. Palaeoecol. 1.) Figure 12.12 Mesozoic palaeocommunities developed across Alpine Europe. Numbers 1 to 7 refer to the seven different biotypes described on the...

Lqd

Figure 3.6 Processes of breakage and diagenesis of fossils. Dead organisms may be disarticulated (a) or fragmented (b) by scavenging or transport, abraded (c) by physical movement, bioeroded (d) by borers, or corroded and dissolved (e) by solution in the sediment. After burial, specimens may be flattened (f) by the weight of sediment above, or various forms of chemical diagenesis, such as the replacement of aragonite by calcite (g) may take place. ones), the energy of currents and grain size of...

Bryozoa

Laurasia And Gondwanaland

Besides these, there were the Bryozoa, a small kind of Mollusk allied to the Clams, and very busy then in the ancient Coral work. They grew in communities, and the separate individuals are so minute that a Bryozoan stock looks like some delicate moss. They still have their place among the Reef-Building Corals, but play an insignificant part in comparison with that of their predecessors. Box 12.5 Tethyan brachiopods in Greenland a Cretaceous Gulf Stream current Brachiopods can give clues about...

Box Turbidite timing

The mode of preservation of trace fossils can show whether they were produced before or after a major sedimentary event, such as a turbidite flow. Turbidites are underwater avalanches, or gravity flows, that may transport vast quantities of sediment rapidly into deeper waters. The Lower Silurian mudstones and sandstones of central Wales and the Welsh coast have long been known as a source of trace fossils that belong to different environments within the deep-ocean Nereites ichnofacies. Crimes...

Ecdysozoa arthropods

Arthropods - such as lobsters, spiders, beetles and trilobites - have legs, a segmented body plan with jointed appendages and the ability to molt. The first major arthropod faunas of the Early Cambrian appear bizarre by modern standards but probably were no more morphologically different to each other than are living faunas. A number of arthropod-like animals in the Ediacara biota suggest an ancient origin for the phylum. Trilobites appeared in the Early Cambrian and during the Paleozoic...

Box Echinoderm classification

In broad terms, the Echinodermata may be divided into two main sister groups - the stalked pel-matozoans and the mobile eleutherozoans. But there are a number of more bizarre Lower Paleozoic forms, known from only a few specimens at single localities, which are difficult to classify at present. The classification is based on a number of key features the main body of the animal, enclosed by plates (the theca or test), areas bearing tube feet (ambulacra) with perforations or holes (brachioles)...

Box Plugging the leaks experimental morphology of archaeocyaths

It is often extremely difficult to reconstruct the life modes of long-extinct organisms that apparently lack modern analogs (see p. 150), particularly when the entire phylum is extinct. In an innovative experimental biomechanical study Michael Savarese (then at Indiana University) constructed models of the three main archaeocyathan morphotypes (aseptate, porous septate and aporous septate), and subjected each to currents of colored liquid in a flume (Fig. 11.12). The first morphotype, a...

Evolutionary Trends Within The Mollusca

A spectacular variety of mollusk morphotypes and life modes evolved during the Phanero-zoic, from the simple body plan of the arche-mollusk. Despite the diversity of early mollusks in the Cambrian, the phylum was not notably conspicuous in the tiered suspension-feeding Box 13.8 Gradualistic evolution of belemnites There are relatively few long fossil lineages that can be used to demonstrate either phyletic gradualism or punctuated equilibria. Most of the best case studies (see p. 124) are based...

Box Brachiopod classification

Recent cladistic and molecular phylogenetic analyses have shown that the traditional split of the phylum Brachiopoda into the Inarticulata and Articulata is incorrect, and instead there are three subphyla, the Linguliformea, Craniiformea and Rhynchonelliformea. All three have quite different body plans and shell fabrics (Fig. 12.2). The linguliformeans contain five orders united by organo-phosphatic shells the inclusion of the paterinides is the most problematic since the group shares some...

Boby And Trace Fossil In Paleobiology

First traces with three-lobed lower surface Figure 19.16 Trace fossils may help to define the Precambrian-Cambrian boundary, and to flesh out detail about the Cambrian explosion. Jensen (2003) identified seven trace fossil zones, each characterized by trace fossils of increasing complexity. Evidence for trilobites, and arthropods in general, is signaled first by trace fossils and then by body fossils. Prot, Proterozoic. (Drawing by Simon Powell.) do not evolve....

Fossils In Fold Belts

One bad fossil is worth a good working Rudolf Trumpy, eminent Alpine geologist Fossils from the deformed zones of mountain belts are rare but important. Relatively few paleontologists study these fossils because they are usually poorly preserved, and are metamorphosed and tectonized fossils in oro-genic or mountain-building zones are also rare and difficult to collect from often hazardous terrains. Nevertheless, fossils are of fundamental importance in the formulation of tectonic models,...

The Line To Humans

The Primates is one of the oldest of the modern placental mammal groups. The name primate (from primus, first) does not refer to this, but to the fact that humans are primates, and so first among animals the namer, Homo sapiens (wise person), has the privilege of choosing the name For most of their history, the primates were a rare and rather obscure group. All primates share a number of features that give them agility in the trees (mobile shoulder joint, grasping hands and feet, sensitive...

Adaptations

Epifaunal - hard substrate (1) (plenipedunculate) Epifaunal - soft substrate (2) (rhizopedunculate) Orthides, rhynchonellides, spiriferides and terabratulides Pseudofaunal (7) and inverted (8) Free-living (9, 10) Cyrtia, Chonetes, Neothyris and Terebratella Figure 12.9 Brachiopod lifestyles. (Courtesy of David Harper and Roisin Moran.) number of quite different non-articulated and articulated taxa were cemented to the substrate, whereas some groups evolved clasping spines to help stabilize...

Lamiae Piscis Capvt

Figure 1.7 Nicolaus Steno's (1667) classic demonstration that fossils represent the remains of ancient animals. He showed the head of a dissected shark together with two fossil teeth, previously called glossopetrae, or tongue stones. The fossils are exactly like the modern shark's teeth. Figure 1.7 Nicolaus Steno's (1667) classic demonstration that fossils represent the remains of ancient animals. He showed the head of a dissected shark together with two fossil teeth, previously called...

Dpl

Ing carbon and oxygen to carbon dioxide and water, according to this equation Microbial decay can also take place in anaerobic conditions, that is, in the absence of oxygen, and in these cases nitrate, manganese dioxide, iron oxide or sulfate ions are necessary to allow the decay to occur. The second set of factors controlling decay, temperature and pH, may be the most important. High temperatures promote rapid decay. Decay proceeds at normal high rates when the pH is neutral, as is the case in...

Box Classification of fishes

Fishes form a paraphyletic grouping, consisting of several distinctive clades of swimming vertebrates. Ordovician and Silurian records of placoderms, acanthodians, chondrichthyans and osteichthyans are mainly isolated scales and teeth these groups are best known from the Devonian onwards. A paraphyletic group of jawless fishes, including armored and unarmored Paleozoic ostraco-derms, and modern lampreys and hagfishes Heavily armored fishes with jaws and a hinged head shield Mid Silurian to Late...

Uza

Fossil Atrypa

Figure 12.2 Classification and stratigraphic distribution of the Brachiopoda. (Courtesy of Sandra Carlson.) at the time of deposition. The ratio of isotopes within the crystal lattice of the brachiopod shell was often controlled by the provenance of the chemical elements (marine or terrestrial) and temperature and salinity of the sea-water. Carbon, oxygen and strontium isotopes are particularly useful. Devonian brachiopod shells from North America, Spain, Morocco, Siberia, China and Germany...

Box Dinosaur behavior

Behavioral Trace Fossil

Dinosaur tracks are probably the most familiar trace fossils, and they can tell us a great deal about how the dinosaurs lived. Some dinosaur track sites cover huge areas, and may reveal hundreds or thousands of footprints, often in long trackways, sometimes representing numerous different species. It is fascinating to use these trackways to speculate about ancient behaviors - but you have to be careful It is important to check whether all the tracks were made at the same time - do they overlap...

Rise Of The Mammals

Marsupials Southern Continents

The first mammals, small insect eaters in the Late Triassic and Early Jurassic (see p. 450), probably hunted at night. Mammals remained small through most of the Mesozoic and they did not achieve high diversity, perhaps held in check in some way by the dinosaurs. Several lines of insectivorous, carnivorous and herbivorous forms appeared, some of them adapted to climbing trees. Most Mesozoic mammals were small, and a recent find from China proved to be an exception (Box 17.4). Nonetheless, most...

Co

Figure 9.8 Stratigraphie ranges of the main foraminiferan groups. Based on various sources. Figure 9.8 Stratigraphie ranges of the main foraminiferan groups. Based on various sources. Figure 9.9 Descriptive morphology of the radiolarians. Figure 9.9 Descriptive morphology of the radiolarians. The acritarchs are a mixed bag of entirely fossil, hollow, organic-walled microfossils that are impossible to classify. The acritarchs are probably polyphyletic they include a wide range of forms, probably...

Class Scaphopoda

Scaphopods are generally rare as fossils. The Scaphopoda, or elephant-tusk shells, have a single, slightly curved high conical shell, open at both ends Fig. 13.25a . They lack gills and eyes, but have a mouth equipped with a radula and surrounded by tentacles they also possess a foot, similar to that of the bivalves, adapted for burrowing. Scaphopods are mainly carnivorous, feeding on small organisms such as foraminiferans and spending much of their life in quasi-infaunal positions within soft...

The origin of seeds

The first plants with seeds are known from Late Devonian rocks, and seed bearers rose to prominence during the Carboniferous. After the end of the Carboniferous, and the extinction of arborescent lycopsids, ferns and horsetails, seed-bearing plants, or gymnosperms, took an increasingly dominant role in floras around the world. Seeds in gymnosperms are naked, that is, they are not enclosed in ovaries as they are in flowering plants angiosperms . Seeds follow from the fertilization of an ovule,...

Box The chitinozoan Rosetta Stone

Chitinozoan

But what really were chitinozoans Material from the Ordovician of Estonia, described as the chitinozoan Rosetta Stone, may have partially solved the problem. Individual vesicles are linked together in a coiled, chain-like structure each vesicle belongs to the same species, Desmochitina nodosa Eisenack Fig. 9.22 . It is unlikely that these were eggs of a metazoan, because larvae would be unable to escape from the tightly sealed and connected chambers. Therefore Paris and Nolvak 1999 postulated...

Origin Of The Vertebrates

The skeleton of vertebrates is made from bone and cartilage. Bone consists of a network of collagen fibers on which needle-like crystals of hydroxyapatite a form of apatite, calcium phosphate, CaPO4 accumulate. Hence bone has a flexible component and a hard component, which explains why bones may undergo a great deal of strain before they break, and also why bones do not break along simple brittle faces. Cartilage is a flexible, gristly tissue, usually unmineralized, and containing collagen and...

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Isograptus Bilder

Figure 15.22 Generalized phylogenetic model for rhabdopleurid and graptolite evolution. From Rickards amp Durman 2006. Figure 15.22 Generalized phylogenetic model for rhabdopleurid and graptolite evolution. From Rickards amp Durman 2006. The Dendroidea is the older of the two main groups with important geological records, first appearing in the Middle Cambrian and disappearing during the Late Carboniferous. The dendroid rhabdosome was multibranched, like a bush, with its many stipes connected...

Eod

Figure 16.10 Evolution of the ray-finned bony fishes a the Carboniferous palaeonisciform Cheirodus, a deep-bodied form b the Triassic holostean Semionotus c the Cretaceous teleost Mcconichthys d evolution of actinopterygian jaws from the simple hinge of a palaeonisciform left to the more complex jaws of a holostean middle and the fully pouting jaws of a teleost right . a, b, based on Moy-Thomas amp Miles 1971 c, based on Grande 1988 d, based on Alexander 1975. Figure 16.10 Evolution of the...

Mesozoic Arms Race

Figure 13.26 Stratigraphie range of the main mollusk groups. benthos of the Paleozoic, although many more localized, often nearshore, assemblages were dominated by mollusks. During the Paleozoic, bivalves were common in nearshore environments, often associated with lingulide brachiopods, although the class also inhabited a range of deeper-water clastic environments and by the Late Paleozoic bivalves had invaded a variety of carbonate environments. However, at the end of the Paleozoic, the...

Class Gastropoda

Gastropoda Cypr

The gastropods, the belly-footed mollusks, are the most varied and abundant of the mol-luskan classes today. The group includes the snails and slugs, forms both with and without a calcareous shell. During a history spanning the entire Phanerozoic, gastropods evolved creeping, floating and swimming strategies together with grazing, predatory and parasitic trophic styles. Most gastropods are characterized by torsion in which the mantle cavity containing the gills and anus, excretory and...

Box Dating origins

There was a sensation in 1996 when Greg Wray of Duke University and colleagues announced new molecular evidence that animals had diversified about 1200 Ma. This estimate predated the oldest animal fossils by about 600 myr. In other words, the molecular time scale seemed to be double the fossil age. This proposal suggested three consequences i the Precambrian fossil record of animals and presumably all other fossils was even more deficient than had been assumed ii the Cambrian explosion,...

Box Columnal classification

The majority of crinoid assemblages are represented by disarticulated ossicles. Conventional taxonomy based on a description of complete, articulated specimens is thus not possible. Nevertheless, ossicles have many distinctive features, arguably with more well-defined characteristics than many groups of macrofossils Fig. 15.3 . Single stems consist of many ossicles with a central canal or lumen usually carrying nerve fibers. Both the ossicles and lumens have distinctive shapes that are the...

The Origin Of Life

There have been many scientific models for the origin of life, some of them now rejected by the evidence, and others still available as potentially valid hypotheses Medieval scholars believed that many organisms sprang into life directly from nonliving matter, a form of spontaneous generation. For example, frogs were said to arise from the spring dew and maggots were said to come to life in rotting flesh. However, careful tests proved that there was no truth in these ideas. Louis Pasteur in...

Class Cephalopoda

Siphuncular

The cephalopods are the most highly organized of the mollusks, with the greatest complexity of any of the spiralian groups. The close association of a well-defined head with the foot modified into tentacles is the source of their name, meaning head-footed. High metabolic and mobility rates, a well-developed nervous system, and sharp eyesight associated with an advanced brain, are ideal adaptations for a carnivorous predatory life mode. The funnel or hyponome is also modified from the foot, and...

Early Mollusks

The Early Cambrian was a time of experimentation, with a variety of short-lived, often bizarre, molluskan groups, such as the helcio-nelloids, dominating many faunas Peel 1991 . Most workers now agree that the first mol-lusks were descended from forms like living flatworms - probably spiculate animals with radula and gills situated posteriorly. These mollusks were similar to modern soft-bodied aplacophorans, a group of shell-less mollusks. The aplacophorans and the shelled mollusks shared a...

Taphonomy and the quality of the fossil record

Plants and animals with hard tissues are most frequently preserved in the fossil record. Soft tissues usually decay rapidly, but rapid burial or early mineralization may prevent decay in cases of exceptional preservation. Physical and chemical processes may damage hard tissues during transport and compaction. Plants may be preserved as permineralized tissues, coalified compressions, cemented casts or as hard parts. There has been a longstanding debate about the fidelity and quality of the...

Box The Rhynie Chert a window on earliest land life

Rhynie is a remote village in northeast Scotland consisting of only 50 or so houses the bus stops there once a day. In 1914, Dr William Mackie, a physician, found traces of plant fossils in some speckled black and white chert rocks. He cut thin sections and took his specimens to Glasgow, where Robert Kidston, the foremost expert in Britain on floras of the Carboniferous, confirmed that the chert contained nearly perfectly preserved plants. Kidston, together with William Lang, Professor of...

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Pathological Trilobites

Figure 14.14 Pathological trilobites a Onnia superba - the fringe in the lower part of the photograph has an indentation and a smooth area, probably regeneration following an injury during molting x4 b Autoloxolichas - the deformed segments on the left-hand side may be either genetic or the result of repair following injury x3 and c Sphaerexochus - only two ribs are developed on the right-hand side, probably a genetic abnormality x25 . Courtesy of Alan Owen. Figure 14.14 Pathological trilobites...

Box How many species are there today

So far, 1.7-1.8 million species of plants and animals have been named and described formally about 270,000 plant species and over 1 million insects . The rate of discovery of new species is highly variable within different groups of organisms. About three new bird species, about one new mammal genus and some 7250 new insect species are named each year. It might seem easy to use such figures to produce an estimate of global diversity on the assumption that, at some time in the future, all...

Echinoderms

Clearly we stood among the ruins of some latter-day South Kensington Here, apparently, was the Pal amp ontological Section, and a very splendid array of fossils it must have been. . . . The place was very silent. The thick dust deadened our footsteps. Weena, who had been rolling a sea urchin down the sloping glass of a case, presently came, as I stared about me, and very quietly took my hand and stood beside me. And at first I was so much surprised by this ancient monument of an intellectual...

Box Fossil annelids and their jaws

The annelids are segmented protostomes that are represented today by animals such as the earthworms and leaches. Recent species are important, widely distributed, benthic predators and occur from intertidal to abyssal depths. Modern molecular studies suggest they form a sister group to the mollusks and, in fact, share a number of morphological characters such as the possession of chaetae. In general the group has a fairly sparse fossil record, appearing fleetingly in Lagerst tte deposits such...

Ventral

Micraster Fossil Aboral And Oral View

Figure 15.11 Echinoid morphology a internal anatomy in cross-section b dorsal and c ventral views of Echinus. Based on Smith 1984. Figure 15.11 Echinoid morphology a internal anatomy in cross-section b dorsal and c ventral views of Echinus. Based on Smith 1984. The echinoid's various organs are suspended within the test and supported by fluid. The water vascular system copes with a number of functions. The stone canal rises vertically, from the central ring around the esophagus, to unite with...

Evolution And Development

Biologists have long sought a link between ontogeny development and phylogeny evolutionary history . In 1866, Ernst Haeckel, a German evolutionist, announced his Biogenetic Law, that ontogeny recapitulates phylogeny. His idea was that the sequence of embryonic stages mimicked the past evolutionary history of an animal. So, in humans, he argued, the earliest embryonic stages were rather fish-like, with gill pouches in the neck region. Next, he argued was an amphibian stage and a reptile stage,...

Frameworks

Six distinct aspects of Tuscany we therefore recognize, two when it was fluid, two when level and dry, two when it was broken and as I prove this fact concerning Tuscany by inference from many places examined by me, so do I affirm it with reference to the entire earth, from the descriptions of different places contributed by different writers. Nicolaus Steno 1669 The Prodromus of Nicolaus Steno's Dissertation Concerning a Solid Body Enclosed by Process of Nature Within a Solid Before the...

Hemichordates

Hemichordata Devonian

What was the character of the vegetation that clothed this earliest prototype of Europe is a question to which at present no definite answer is possible. We know, however, that the shallow sea which spread from the Atlantic southward and eastward over most of Europe was tenanted by an abundant and characteristic series of invertebrate animals - trilobites, graptolites, cystideans, brachiopods, and cephalopods, strangely unlike, on the whole, to anything living in our waters now, but which then...

Brachiopoda

Pedicle Foramen

It is no valid objection to this conclusion, that certain brachiopods have been but slightly modified from an extremely remote geological epoch and that certain land and fresh-water shells have remained nearly the same, from the time when, as far as is known, they first appeared. Charles Darwin 1859 On the Origin of Species The brachiopods are one of the most successful invertebrate phyla in terms of abundance and diversity. They appeared first in the Early Cambrian and diversified throughout...

Fossil plants

Fossil Bryophytes

Fungi have a long fossil record, perhaps dating back to the end of the Precambrian, but they are not true plants. Green algae, and their relatives, are close to the origin of green plants. Plants moved onto land in the Ordovician and Silurian, a move enabled by the evolution of vascular tissues, waterproof cuticles and stomata, and durable spores. Various non-seed-bearing plants arose during the Devonian, but tree-like lycopsids, equisetopsids and groups such as ferns became established by the...

Regressive Surface Of Marine Erosion

Figure 2.8 Current status of the development of a new, internationally accepted chronostratigraphy for the Ordovician System. New global series and stages are correlated with the comparable chronostratigraphic divisions used in North American and the United Kingdom and Ireland. GSSP, global standard section and point. Figure 2.8 Current status of the development of a new, internationally accepted chronostratigraphy for the Ordovician System. New global series and stages are correlated with the...

Subphylum Hexapoda

The Hexapoda, essentially the insects, can be divided into pterygotes with wings and apterygotes without wings and include the springtails, dragonflies, cockroaches and locusts. The group may prove to have as many as 10 million living species when the rich faunas of the tropics have been completely described. The subphylum also includes the onychophorans, with flexible segmented bodies and unjointed limbs propelled by changes in blood pressure analogous to the water vascular system of the sea...

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Cordaites Reconstruction

Upland cordaite-dominated vegetation on calcrete soils Lowland vegetation dominated by cordaites with minor pteridosperms, sphenopsids, and rare lycopsids Figure 18.19 The early conifer Cordaites, about 25 m tall. Based on Thomas amp Spicer 1987. Figure 18.19 The early conifer Cordaites, about 25 m tall. Based on Thomas amp Spicer 1987. of China, but seen today as a typical urban tree in parts of North America and Europe. Ginkgos were more diverse in the Mesozoic. Leaf shape varies from the...

Spicule Morphology

Commonly the spongin skeletons decay and unfused spicular skeletons disintegrate shortly after death leaving only a selection of hard parts, such as spicules Fig. 11.5 . Spicule morphology is thus a fundamental means of identification of those spiculate forms. Spicules may be large megascleres , acting as part of the skeleton, or small microscleres , scattered throughout the sponge and rarely preserved. Five basic types of spicule have been recognized 1 Monaxons single axial forms that may grow...

Growth And Form

Bivariate Analysis Brachiopods

Paleontologists must interpret fossil species, and their ranges of variation, solely from the morphology, or external shape, of the specimens. There are problems in deciding where one species ends and another begins. When there are close living relatives, it may be possible to compare the modern species with the fossils. But how are paleontologists to decide just what is a species of dinosaur or trilobite For modern plants and animals, system-atists ideally apply the biological species concept...

Merodont Hinge Ostracode

Figure 14.22 Descriptive terminology of the ostracode animal a , including muscle scars b and hinge structures c . Based on Armstrong amp Brasier 2005. Figure 14.22 Descriptive terminology of the ostracode animal a , including muscle scars b and hinge structures c . Based on Armstrong amp Brasier 2005. Articulatory structures are variably developed along the hinge line. Three main types of hinge are known Fig. 14.22c . Adont hinges lack teeth but have a long median element on the right valve...

Box Jumping bristletails

Ichnogenus

The slab in Fig. 19.1 shows a clean, slightly undulating surface, with some long cracks and obscure little markings here and there. But is there anything of importance on the slab It might not at first seem so. The slab comes from the Lower Permian Robledo Mountains Formation of southern New Mexico Minter amp Braddy 2006 , where most surfaces show tracks of one sort or another amphibians, reptiles, scorpions, spiders, millipedes and insects. Trace fossils are...

Wileyblack Well

A John Wiley amp Sons, Ltd., Publication This edition first published 2009, 2009 by Michael J. Benton and David A.T. Harper Blackwell Publishing was acquired by John Wiley amp Sons in February 2007. Blackwell's publishing program has been merged with Wiley's global Scientific, Technical and Medical business to form Wiley-Blackwell. Registered office John Wiley amp Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices 9600 Garsington Road, Oxford, OX4 2DQ,...

1

Ribozyme Replication Protocell

Where an RNA replicase and a self-replicating membrane-bound vesicle combine to form a protocell. Inside the vesicle, the RNA replicase functions, and might add a function to improve the production of the vesicle wall through a ribozyme. At this point, the RNA replicase and the vesicle are functioning together, and the protocell has become a living cell, capable of nutrition, growth, reproduction and evolution. Read a general introduction to RNA world at http www.blackwellpublishing.com...

Box Alternating ichnofacies

Ichnofacies

Many sedimentary sequences show a mix of ichnofacies, as would be expected, since no ichnofacies is exclusive to a single location or water depth. The Cardium Formation of Alberta, Canada has produced abundant trace fossils from a sequence of muds and sandstones Pemberton amp Frey 1984 Fig. 19.14 . The normal quiet-water sedimentation produced mud, silt and fine sand layers, and diverse trace fossils of the Cruziana ichnofacies, mainly representing the activities of mobile carnivores and...

Box Ediacaran arthropods

Trilobite Ontogeny

Are they or aren't they Some paleontologists believe they can identify some of the Ediacaran animals as arthropods or proto-arthropods others dispute this. Parvancorina Fig. 14.2 , for example, is a possible candidate, with its shield-shaped outline, strong axial ridge and arched anterior lobes, together with a convex profile. It really looks like a juvenile trilobite molt stage, but did not have a mineralized skeleton. Not convinced Beautifully preserved fossils from a new Cambrian Lagerst...

Box Palynology

Cordaitales Classification

Palynomorphs, fossil pollen and spores, provide evidence about ancient paleoenvironments, often when other fossils are absent, and they are key tools in biostratigraphy see pp. 26-32 . Fossil pollen and spores have proved to be essential in understanding the biostratigraphy of the Late Paleozoic, Mesozoic and Cenozoic, especially in terrestrial rock sequences. Pollen analysis is also a routine part of studies of Quaternary paleoenvironments, especially those studied by archeologists. They can...

Box Classification of the tracheophytes

Tracheophytes are the vascular land plants, and include modern ferns, horsetails, conifers and flowering plants, as well as numerous extinct groups. The basal groups are distinguished in terms of branching patterns and sporangial morphology. Simple vascular plants with dichotomously branching stems and terminal sporangia Mid Silurian to Early Devonian Small to large plants with lateral sporangia and usually small leaves Horsetails vertical stems with jointed structure and a whorl of fused...

Box Dinosaur speeds

When you walk along a beach, you leave tracks with a particular stride length the distance from one foot-fall to the next by the same foot . If you begin to run, the stride length increases, and the faster you go, the longer the stride length. An English expert in biomechanics, R. McNeil Alexander, spotted something more there was a constant relationship between stride length and speed, providing you took account of the size of the animal measured by the height of the hip from the ground , and...

Funnel Organism

Solenogastres 1 ' Caudofoveata J ' Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda Figure 13.1 Pseudocladograms of molluskan evolution hypothetical archemollusk HAM evolution integrated with a cladistic-type framework. Model a demonstrates a split into the Aculifera and Conchifera, whereas b indicates a division into the Aplacophora and Testaria. Based on Sigwart amp Sutton 2007. Box 13.2 Kimberella and Odontogriphus join the mollusks A modest-sized, disk-shaped fossil...

Subphylum Trilobitomorpha

The trilobitomorphs are highly derived arthropods lacking specialized mouthparts, and with tagmata comprising the cephalon, thorax and pygidium, together with trilobitomorph appendages that have lateral branches developed from the walking limbs. The trilobito-morphs include mainly the trilobites and over 15,000 species are known. Trilobites were a unique and very successful arthropod group, common throughout the Paleozoic until their extinction at the end of the Permian. There is no doubt that...

D

Homotryblium

Figure 9.10 Some radiolarian morphotypes Lenosphaera x100 , Actinomma x240 , Alievium x180 , Anthocyrtidium x250 , Calocyclas x150 and Peripyramis x150 . was a monument to our ignorance. Although many more taxa have been described since, and their value in biostratigraphic correlation has been proved, uncertainty still surrounds the origin and affinities of the group. Similarity, however, with the cyst stages of modern prasinophytes and dinoflagellates suggests a relationship to primitive green...

Crinoids In Microscale

Ordovician Stromatoporoid Tabulate

Box 11.9 Corals and the Earth's rotation Through time, the Earth has changed its rate of rotation, and days have become longer. This extraordinary discovery has come from detailed analysis of the growth bands on coral epithecae. Well-preserved corals often display fine growth lines, grouped together into thicker bands the former are thought to reflect daily growth while the latter bands are monthly growth cycles, controlled by the lunar orbit. A set of more widely spaced bands may represent...

Box Undertracks of the emu

Experts on dinosaur tracks have been aware for a long time about undertracks. Huge animals such as dinosaurs made very deep footprints when they walked over soft sediment. Sometimes the print shape was transmitted for a meter or more down through the layers of sediment below the layer on which the animal walked, and this means that many dinosaur tracks are actually undertracks, if they are viewed on a lower layer. There have been many experiments to show how tracks are altered by the...

Box Insects take to the airways

Arthropod Woodwardi

Fossil insects with functional wings are first reported from Mid Carboniferous strata. These insects were extraordinary Fig. 14.20 the dragonfly Meganeura had an incredible wingspan of 70 cm. Intense aerobic activity such as powered flight suggests that atmospheric oxygen levels at the time were unusually high. But how effective was Meganeura as a flyer Robin Wootton and his colleagues 1998 have identified so-called smart features that capitalized on both upstroke and downstroke movements of...

Subphylum Myriapoda

Silurian Myriapod

The myriapods are a varied group comprising the millipedes, centipedes, symphylans and pauropods. They first appeared during the Mid Silurian, when Kampecaris-like forms were responsible for a variety of terrestrial trails Box 14.6 . Some of the largest forms, for example the giant Arthropleura, nearly 2 m long, hoovered their way through the lush, green vegetation of the Late Carboniferous forests. The myriapods were the first animals to colonize the land. Heather Wilson and Lyall Anderson...

Box The Chronos initiative

Glossopteris

There are a number of different geological time scales, developed by different groups of authors for different intervals of geological time, and many different ways to analyze time series data of this type. The Chronos Greek for time project is a web-based initiative that seeks to centralize all the various time scales and analytic tools through one web portal. This is a chronometric rather than chronostratigraphic system and thus deals with radiometric age rather than the relative order of...

Box Living Nautilus

Diagram Connecting Ring Ammonoidea

Living Nautilus has allowed biologists and paleontologists to model the functions and life modes of the ancient ammonites by using a modern analog. But despite the similarity of their respective shells, coleoids are, in fact, more closely related to ammonites than modern nautiloids, and thus better behavioral analogs may be found within the coleoids Jacobs amp Landman 1993 . It is probable that coleoid-type swimming mechanisms probably evolved prior to the loss of the body chamber in the...

Dinosaurs And Their

The diapsids see p. 447 were initially small to medium-sized carnivores that never matched the abundance of the synapsids in the Car boniferous or Permian. Things began to change during the Triassic, perhaps as a result of the end-Permian extinction event, which had such a devastating effect on therapsid communities. Small and large meat eaters such as Erythrosuchus Fig. 17.1a appeared, one of the first of the archosaurs, a group that was later to include the dinosaurs, pterosaurs, crocodilians...

Jaws And Fish Evolution

The basal vertebrates, including conodonts, lacked jaws, and jaws probably evolved during the Ordovician. Study of the anatomy of modern vertebrates suggests that jaws may have evolved from the strengthening bars of cartilage or bone between the gill slits, each of which consists of several elements, all linked by tiny muscles. The transition cannot be followed in fossils because the gill skeleton of jawless fishes was not mineralized. Molecular biologists have even suggested that the origin of...

Kilbuchophyllum

Figure 11.29 Scleractinian morphology a longitudinal and b transverse sections, and c mode of septal insertion. algae and stromatoporoids were usually more important. Nevertheless, frameworks dominated by colonial tabulates, and to a lesser extent rugosans, do occur, particularly during the Mid Paleozoic. Growth bands on the latter have provided us with a Paleozoic calendar Box 11.9 . Pioneer and climax communities have been described from a number of Silurian and Devonian successions Fig....

Stromatoporoids

Jurassic Stromatoporoids

I aclonal, solitary clonal, modular degree of integration Figure 11.6 Stratigraphic distribution of reef-building sponges and related parazoans, together with the sderactinian corals. Late Carboniferous the chaetetid calcified sponges were important reef builders. In the Permian and mid-Triassic, structures involving sphinctozoans were common and the Mid to Late Jurassic was marked by bioherms of lithistid demosponges, while the hexactinel-lids migrated into deeper-water environments. Jurassic...

Kidney Of Bivalves

Palaeontology Arca Pallial Line

Figure 13.4 Theoretical morphospace created by the computer simulation of shell growth a and some computer simulations matched with reality b . a, based on Raup 1966 b, from Swan 1990. burrowing and boring strategies together with migrations to freshwater habitats were secondary innovations. There are over 4500 genera of living bivalves, with fewer than half of that number described from the fossil record. In view of the wide range of life strategies and their relationships to particular...

Chlorobionta

Chlorobionta

Figure 18.4 Cladogram showing the postulated relationships among the major groups of vascular land plants. Some synapomorphies that define particular nodes are Chlorobionta chlorophyll b , Charophyceae Embryophyta cell structure , Embryophyta alternation of generations , Tracheophyta vascular canals tracheids and secondary thickening and Spermatopsida seeds . Read more about the deep green project to establish a complete phylogeny of green plants at http ucjeps.berkeley. edu bryolab GPphylo ....

Hexactinellida

Prismodictya Devonian-Carboniferous Prismodictya Devonian-Carboniferous Figure 11.3 Some examples of the main groups of sponges Archaeoscyphia x0.25 , Siphonia x0.4 and 0.8 , Protospongia x0.4 , Hydnoceras x0.25 , Prismodictya x0.6 , Rhaphidonema x0.8 , Corynella x0.8 and Astraeospongium x0.4 . Figure 11.3 Some examples of the main groups of sponges Archaeoscyphia x0.25 , Siphonia x0.4 and 0.8 , Protospongia x0.4 , Hydnoceras x0.25 , Prismodictya x0.6 , Rhaphidonema x0.8 , Corynella x0.8 and...

Box The nine ichnofacies

Thalassinoides

The Nereites ichnofacies Fig. 19.13a is recognized by the presence of meandering pascichnia such as Nereites, Neonereites and Helminthoida, spiral pascichnia such as Spirorhaphe, and agrichnia such as Paleodictyon and Spirodesmos. Note that the whole concept of agrichnia is debated the most commonly quoted example, Paleodictyon, has been interpreted as the mold of a deceased, soft-bodied, colonial-type organism, although others dispute this new view. Vertical burrows are almost entirely absent....

Protozoa

Microgranular Foraminifera

Protozoans are neither animal nor plant, but single-celled eukaryotes that commonly show animal characteristics such as motility and heterotrophy some groups are able to form cysts. Most are about 50-100 m in size and are very common in aquatic environments and in the soil. They can occupy various levels in the food chain ranging from primary producers to predators and some groups function as parasites and symbionts. Foraminifera are shelled, heterotrophic protozoans, common in a wide variety...

Acknowledgments

We thank the following for reading chapters of the book, and providing feedback and comments that gave us much pause for thought, and led to many valuable revisions Jan Audun Rasmussen Copenhagen , Mike Bassett Cardiff , Joseph Botting London , Simon Braddy Bristol , Pat Brenchley formerly Liverpool , Derek Briggs Yale , David Bruton Oslo , Graham Budd Uppsala , Nick Butterfield Cambridge , Sandra Carlson Davis , David Catling Bristol , Margaret Collinson London , John Cope Cardiff , Gilles...

Box Ammonite heteromorphs

Nipponites Ammonite

One of the more spectacular aspects of ammonite evolution was the appearance of bizarre hetero-morphic different shape shells in many lineages at a number of different times Fig. 13.20 . Heteromorphs first appeared during the Devonian, but were particularly significant in Late Triassic and Late Cretaceous faunas. Some such as Choristoceras, Leptoceras and Spiroceras appeared merely to uncoil Hamites, Macroscaphites and Scaphites partly uncoiled and developed U-bends whereas Noestlingoceras,...

Class Rostroconcha

Relatively recently a small class of mollusks, superficially resembling bivalves but lacking a functional hinge, has been documented from the Paleozoic. Over 35 genera have been described most were originally described as bivalved arthropods. The rostroconchs probably had a foot that emerged through the anterior gape between the shells. However, the two shells are in fact fused along the mid-dorsal line, and posteriorly the shells are extended as a platform or rostrum Fig. 13.25b . Ontogeny...

O

Figure 5.4 Fine-scale evolution in fresh-water snails and bivalves in Lake Turkana, Kenya, through the last 4 myr. The volcanic tuff beds allow accurate dating of the sequence. Major speciation events seem to take place at times of lake-level change are these examples of punctuational speciation, or merely ecophenotypic shifts Based on Williamson 1981. without gaps, abundant fossils throughout and good dating. The problems in testing became evident early on, because sampling was generally not...

Paleoecology and paleoclimates

Fossil organisms provide fundamental evidence of evolution they also allow the reconstruction of ancient animal and plant communities. Paleoecologists study the functions of single fossil organisms paleoautecology or the composition and structure of fossil communities paleosynecology . The paleoecology of fossil organisms can be described in terms of their life strategies and trophic modes together with their habitats virtually all fossil organisms interacted with other fossil organisms and...

Box Rugosan life strategies

Despite the apparent simplicity of rugosan architecture, these corals may have pursued a number of different life strategies Fig. 11.24 . A number of corals, for example Dokophyllum, probably sat upright in the sediment rooted by fine holdfasts extending from the epitheca. Other taxa, such as Holophragma, were initially attached to a patch of hard substrate but subsequently toppled over to rest on the seabed. Grewingkia was cemented to areas of hard substrate. The small discoidal Pal-aeocyclus,...

Chromista

Diatomite Structure Valves Girdle

The chromistans are probably a paraphyletic group of eukaryotes that usually contains chloroplasts with chlorophyll c, which is absent from all known plant groups. The group includes various algae, the coccolitho-phores and the diatoms and the majority are primary producers, functioning as part of the phytoplankton. Nannoplankton, are defined as plankton less than 63 m across, the smallest standard mesh size for sieves. Although the nanno-plankton includes organic-walled and siliceous forms,...

Box Classification of Cnidaria

Cnidarian Calcification

The phylum is characterized by radial symmetry, with the ectoderm and endoderm separated by the mesoglea the enteron has a mouth surrounded by tentacles with stinging cells. The phylum ranges from Upper Precambrian to Recent. The putative medusoid Brooksella, which predates the Ediacara fauna may, in fact, be a trace fossil. The group has a wide range of body plans Fig. 11.18 . This includes six main orders of small, usually polymorphic forms. Each has an undivided enteron and solid tentacles,...

Stromatoporoids Water Flow

Archaeocyaths

Figure 11.8 Stromatoporoid growth modes. Based on Kershaw, S. 1984. Palaeontology 27. Figure 11.8 Stromatoporoid growth modes. Based on Kershaw, S. 1984. Palaeontology 27. poroid skeleton both bivalves and brachio-pods have been seen in borings within stromatoporoids that may have provided some of the first cryptic habitats for Phanero-zoic biotas. Animals with a stromatoporoid grade of organization have been identified from rocks of Botomian age however these forms were apparently short lived....

Survivorship Curve Crustacean

Frequency Polygon Data

Figure 4.4 Schematic size-frequency histograms a right positively skewed, typical of many invertebrate populations with high infant mortality b normal Gaussian distribution, typical of steady-state or transported assemblages c left negatively skewed, typical of high senile mortality d multimodal distribution, typical of populations with seasonal spawning patterns and e multimodal distribution, with decreasing amplitude, typical of populations growing by molting ecdysis . Size of individuals age...

Goj

Ediacaran Cnidae

Figure 10.7 Stratigraphie distribution of the Ediacara biota. Solid triangles, glaciations C, calcified metazoans T, position of the Twitya disks. Based on Narbonne 2005. shallow-water siliciclastic sediments, consisting of clasts of silicic-rich rocks, or volcanic ash, more rarely carbonates or even turbi-dites. The sediments were deposited during specific events, such as a storm, and are usually termed event beds. Deep-water biotas are also known such as those from Mistaken Point in...