Abstract Tracks of small quadrupedal ornithischians with five manual and four pedal digits have been recorded from sedimentary rocks near the Late Jurassic–Early Cretaceous (Tithonian–Berriasian) boundary in NE Thailand and British Columbia. These are compared with larger tracks of gracile, quadrupedal ornithopods from the earliest Cretaceous of Spain and smaller tracks of a quadruped of unknown age from Zimbabwe. The Thai and Canadian tracks are similar to the Early Jurassic (Liassic) ichnogenus Anomoepus and the small ornithopod tracks from the Late Jurassic of Spain. They are the only known post-Liassic ornithischian tracks in which up to five discrete manus digit impressions are clearly visible. Based on strong heteropody (manus much smaller than pes) in all cases we infer an ornithopod trackmaker rather than another ornithischian. The scattered, but widespread earliest Cretaceous occurrence of this ichnotaxon, herein assigned to Neoanomoepus perigrinatus ichnogen. and ichnosp. nov., on the basis of type material from Canada, suggests that these hitherto unknown earliest Cretaceous ichnofaunas may represent a radiation of small basal ornithopods (pes length less than 15 cm), appearing before the widespread radiation of large ornithopods (pes length up to 60 cm or more) later in the Neocomian (Valanginian–Barremian), Aptian–Albian and Late Cretaceous. The primitive condition of the trackmaker is indicated by the pedal and manual morphology, which consists of four and five digits respectively that are not enclosed by well-developed fleshy padding or integument. In contrast, all larger Cretaceous ornithopod tracks, mostly from post-Berriasian strata, have only three pedal digits enclosed in fleshy pads and a manus in which all functional digits are reduced and enclosed by substantial flesh.

Abstract: Organisms are homeostatic organic wholes. Their organization is understandable, and fractally repeated, from the level of the cell to whole individual organisms, through higher taxonomie groups up to the level of the biosphere. This is not fully appreciated by most biologists and paleontologists owing to emphasis on investigation of the parts (individual organs) that constitute static anatomy, rather than the dynamic morphological interrelationships. The morphodynamic approach, which is largely synonymous with a holistic heterochronic approach, also allows us to view organisms as complex systems: i.e., as manifestations of iterative or recursive fractal organization. Using the Schadian paradigm, already successfully applied to an understanding of modern mammals, and the relationships between morphology (form), physiology, and behavior, it is possible to gain insight into reiterating, recursive, or fractal patterns of organization in dinosaurs, pterosaurs, and other extinct archosaurs. Once these whole-body morphodynamic relationships are understood, as inherent, intrinsic, or “formal” aspects of vertebrate development, all natural groups of organisms can be seen in a new light: i.e., recurrent patterns of morphological organization (convergence) are seen as necessary correlates of physiological organization and behavior. In turn, all these organic attributes help us understand dynamic evolutionary development of any natural taxonomic group (clade). Thus, ontogeny reiterates and creates phylogeny (and vice versa) in a series of fractal, recursive manifestations of form, physiology, and behavior. Appreciation of the intricacy of this complex fractal organization is an exercise in pattern recognition, with surprising implications, especially for paleontology. First, it confirms the interrelatedness of all organisms, one of the central tenets of modern evolutionary theory. Second, it supports the view that higher natural taxonomic groups, already recognized by biology and paleontology, are in reality superorganisms, with inherently similar organizational structure, modified only by spatial and temporal scaling (heterochrony). Thus, all have their own inherent spatio-temporal developmental trajectories (form, life span, and relative emphasis of proximal and distal—or inner and outer/peripheral organs). Third, convergence and iterative evolution can be understood as an inherent quality of a reiterating or recursive fractal system and not merely as an adaptation to external pressures of the environment. This inference is strongly supported by evo-devo studies. Fourth, the modification of the natural organic system, in part or wholly, will lead to a compensation or ripple effect throughout the whole system. Moreover, the phylogeny of a particular group may not be controlled by external environmental pressures to the degree often supposed. Rather, such phylogenies may be natural heterochronic cycles of repeated growth at levels of organization corresponding to higher taxonomic groups (= superorganisms). Such intricate, inherent (or formal) organic organization reveals lawful patterns of morphological relationships that extend beyond isolated and/or shared character recognition. Thus, it may be possible to predict the general form and physiology of the whole animal from an analysis or understanding of the parts (a process akin to modeling). This is particularly useful in paleontology. The morphodynamic approach does more than revive Cuvier’s principle of the correlation of “some” parts. It impels us to recast our previously static understanding of morphology in the light of the inherently dynamic nature of complex systems, showing us how “all” parts are ultimately related.

Abstract New finds of pterosaur tracks (cf. Pteraichnus) from the Summerville and Sundance formations (Late Jurassic) of western North America associated with elongate scrape marks and small circular paired depressions indicate that pterosaurs could swim, or at least float in water, and that they may have fed on small animals living at the sediment surface in shallow water. In this respect their behaviour resembled certain seabirds. The ichnological evidence for pterosaur ‘swim’ and ‘feeding’ traces consists of scrape marks interpreted as traces left when the paddling limb of a pterosaur registered on the substrate, and small circular paired depressions as traces left when the beak of a pterosaur was probing for food. Such traces resulting from aquatic activity are consistent with the nearshore environments in which pterosaur bones and trackways have been found. There is growing evidence for an extensive and complex Pteraichnus ichnofacies in the Late Jurassic of western North America; over 80 specimens have been collected with many more remaining in the field. In particular we draw attention to the large quantitative data base that is available for morphometric, size-frequency studies and the potential for behavioural studies of individual locomotion and flocking. In addition the sites hold considerable promise for understanding what appears to be the world's largest pterosaur ichnofacies in the context of ancient depositional environments and regional sequence stratigraphy.

Volcanism significantly affects the biostratigraphic record by contributing to special preservation of fossil floras and faunas, and by modifying the paleoenvironments in which they developed and evolved. The main local or near-source influences of ash and tephra falls, and downslope pyroclastic and debris flows, are rapid burial of biotas that are either in situ or transported only short distances. Large eruptions may cause similar rapid burial farther from source. Volcanism also affects the development of local substrates and the configuration of lakes and drainages near source, and on a regional scale, causes the construction of volcanic islands. In all cases, new habitats are provided for biotas that may subsequently be represented in the biostratigraphic record. On the local, regional, and global scale, volcanogenic emanations of CO 2 , H 2 S, SO 2 , and other gaseous and particulate material are a significant cause of climatic perturbation leading to temperature fluctuations, and in some cases, disequilibrium in global biogeochemical cycles. This suggests that volcanism may have contributed more to the Cretaceous-Tertiary extinctions and other turnover/extinction episodes than is usually supposed.

An unusual, laminated, spherulitic limestone with cherty layers forms part of a volcanogenic sequence in the Midland Valley of Scotland, 27 km west of Edinburgh. It preserves a cross section of the early Carboniferous terrestrial community. Microcrystalline silica laminae containing inclusions of calcite or dolomite may be primary, and support a hot-spring origin for the deposit. Oxygen isotope analyses of the silica and carbonate are consistent with the precipitation of silica from hot, possibly boiling, hydrothermal solution. Such hot spring waters were presumably heated by hypabyssal intrusives associated with the West Lothian volcanic center, only 5 km to the northwest. Silica was probably precipitated by acidification when such waters entered a very local, fresh-water lake. At the same time, calcium carbonate was precipitated from surface water, due to an increase in temperature and reduction in acidity. Such precipitates covered wide areas of the lake floor and the fossils lying on it. Algal or bacteriogenic precipitation may have been responsible for the formation of accretionary growths around nuclei of wood, other fossils, and rock clasts. The preserved terrestrial biota includes almost-complete individuals of a reptile and of four amphibian groups: temnospondyls, anthracosaurs, loxommatids, and aistopods. These are the oldest known, fully land-going tetrapods. Truly aquatic forms are absent. Invertebrates include: large eurypterids, which may have been partially terrestrial; the oldest known proven terrestrial scorpion ( Gigantoscorpio ); the earliest harvestman “spider”; and millipedes. Several land-plant assemblages are found in the sequence. Permineralized plants show exceptional anatomical preservation when enclosed within accretionary nodules. Fusainized (charred) gymnosperm wood and pleridosperm leaves indicate the presence of wildfires. Fully articulated amphibian skeletons occur within the laminated limestones, whereas only disarticulated skeletons have been collected from the lapilli tuffs. Such taphonomic evidence supports an epiclastic origin for the volcaniclastic rocks, deduced from study of clasts and bedform analysis. Fragments mass-flowed or were rain-washed from the flanks of a small basaltic volcano onto or into an area of sinter deposition.

Diverse anatomically preserved plant assemblages occur abundantly in Lower Carboniferous volcanic sequences in the Midland Valley Basin, Scotland. They are preserved as calcareous permineralizations and as fusain (fossil charcoal). The plants occur in basaltic ashes, lavas, peats, and limestones. Many of the assemblages occur in deposits that are interpreted as products of phreatomagmatic activity. Numerous genera and species occur specifically in volcanic rocks. The volcanic activity may have stimulated the diversification of early ferns and pteridosperms in particular, as well as causing ecological disturbance and vegetational change.

Worldwide volcanism coincident with the end of the Cretaceous provides the source of iridium, shocked minerals, the carbon (CO 2 ) excursion, and the attendant greenhouse effect (from 18 O data). Reproductive stress under greenhouse conditions may have been a deciding factor in extinction of terrestrial fauna. Acidification of the upper ocean due to volcanic CO 2 may be the responsible factor in the K/T nannoplankton event. The K/T transition is characterized by extensive paludification, forming bryophytic bogs, the source of K/T coal beds. Mantle convection is deemed the source of the worldwide volcanism attending the Late Cretaceous. Episodic mantle convection may have been responsible for other extinction events.

Analyses of pollen and spore distribution in samples taken in close stratigraphic succession from several sections of the Neogene Succor Creek, Stinking Water, and Trapper Creek floras indicate that the source-vegetation mosaic at each site was in a state of ecological disequilibrium. All these floras are preserved in volcaniclastic sediments, and in each case the presence of fossiliferous strata is closely linked in both space and time with local eruptive activity. The exposed stratigraphic sections appear to represent relatively short periods of time, probably less than 10,000 yr, excluding unrecognized diastems. In all cases, most of the time represented in the studied sections records successional vegetation rather than a mosaic of community types in equilibrium with the prevailing paleoclimate. In most cases, the ecological dynamics can be related to the disturbance or destruction of forests by local volcanic activity and/or fire, followed by distinctive serai stages, barring further disturbance, leading to the reestablishment of a diverse forest-community mosaic. Many of the megafossil collections from these floras have lacked sufficient stratigraphic control, and most represent a single serai stage or a mélange of serai stages. Reconstructing the megafossil assemblages that correspond to specific stages in the recovery continuum is rarely possible. Pollen spectra characteristic of minimally disturbed communities are rare. Of the three floras studied, the Stinking Water represents the lowest paleoelevation and/or highest paleotemperature of forests dominated by broadleaved taxa throughout the area. Conifer stands were rare and confined to local topographic highs. The Succor Creek area supported a diverse array of broadleaved-dominated forests in the lowlands and conifer-dominated forests on adjacent low slopes, suggesting a cool but equable paleoclimate. The southern part of the Succor Creek area was probably higher and topographically more diverse than the northern part of the area. The Trapper Creek region was higher and/or cooler than the other sites and was dominated by coniferous forest. Broadleaved-dominated communities in the Trapper Creek area were significant only in the recovery intervals following disturbance.

Nonmarine lower Miocene rocks widely exposed in nearly continuous outcrop over approximately 3100 km 2 (1,200 mi 2 ) of the Hartville Table in southeastern Wyoming and western Nebraska indicate a semiarid continental interior, with seasonal climate characterized by sandy ephemeral or intermittent braided streams, interchannel plains mantled by fine-grained volcaniclastic loess, and shallow ephemeral holomictic lakes. These paleoenvironments are recognized on the basis of distinctive sedimentologic, faunal, and taphonomic characteristics. Stream sediments (10 percent or less of total outcrop) are primarily tuffaceous silty sandstones, deposited as reworked pyroclastic debris in wide shallow valleys. These valleys first filled with fluvial fine-grained volcaniclastics, but with the cessation of streamflow in the region, filling was completed by air-fall volcaniclastic loess that blanketed both valleys and interchannel reaches. Fluvial sediments within the valleys include much spatially dispersed mammal bone that had been scavenged and subaerially weathered prior to burial. Waterholes, situated in or adjacent to the valleys, filled with tuff and carbonate mud containing freshwater ostracods, pulmonate gastropods, diatoms, and charophyte algae. These tuffaceous waterhole muds intertongue with fluvial volcaniclastic sediments and are the locus of major mammalian bone beds, the best known preserved at Agate Fossil Beds National Monument. Bones of chalicothere, rhinoceros, and entelodont are common in waterhole bone beds and in fluvial sediments in the region. Massive tuffaceous air-fall silty sandstones (87 percent of outcrop) punctuated by silcrete paleosols were deposited in the interchannel reaches; mammal remains are commonly represented by widely scattered, isolated bones and partial skeletons of young and aged ungulates, chiefly oreodonts and camels, indicative of attritional deaths over time. No bone beds occur. Thin silicified carbonate mudstones (about 2 percent of outcrop) with ostracods, plant debris, and aquatic pulmonate gastropods (but without fish or other aquatic vertebrates) indicate shallow, holomictic, ephemeral lakes that filled with homogeneous micrite mud. These lakes were isolated sheet-like bodies of water unassociated with stream sediments. Following desiccation, lacustrine sediments were commonly overprinted by pedogenic features. Eolian transport of fine pyroclastic detritus into the North American midcontinent was essential to preservation of these sedimentary environments and their rich fossil record. In the Americas and in Africa during the Cenozoic, fine-grained volcaniclastic sediments blanketed large geographic areas within the continental interiors, preserving significant temporal intervals of the vertebrate fossil record. If volcanism had not occurred, these intervals would exist as major hiatuses in our knowledge of vertebrate, particularly mammalian, evolution. The important role of fine-grained volcaniclastics in preservation of mammalian faunas and their associated depositional environments in the Americas and in Africa during the Cenozoic deserves greater emphasis.