Vertebrate Evolution

The exquisite transitional fossil Tetrapodophis e described as a stem-snake with four small legs from the Lower Cretaceous of Brazil e has been widely considered a burrowing animal, consistent with recent studies arguing that snakes had fossorial ancestors. We reevaluate the ecomorphology of this important taxon using a multivariate morphometric analysis and a reexamination of the limb anatomy. Our analysis shows that the body proportions are unusual and similar to both burrowing and surface-active squa-mates. We also show that it exhibits striking and compelling features of limb anatomy, including enlarged first metapodials and reduced tarsal/carpal ossification e that conversely are highly suggestive of aquatic habits, and are found in marine squamates. The morphology and inferred ecology of Tetra-podophis therefore does not clearly favour fossorial over aquatic origins of snakes.

371 Introduction 372 Morphological and molecular data 373 Methods 375 Separate analyses 375 Combined parsimony analyses 375 Combined Bayesian analyses 375 Combined likelihood analyses 376 Results 378 Separate analyses 378 Combined analyses 380 Discussion 383 Weighting morphology and molecules in parsimony and likelihood 383 Snake phylogeny and taxonomy 387

This catalogue presents the Devonian vertebrates of China. The ages of some vertebrate fossils are corrected according to recent biostratigraphic correlations. The vertebrate bio-events in the Devonian of China are also investigated. ln South China, the Early Emsian Event is characterized by a changeover from strong endemic fauna to cosmopoJitan fauna. The endemic Galeaspida become almost extinct after the Mid-Emsian Event. The Late Eifelian Event results in the disappearance of rnany placoderms. The Antiarcha have their last radiation in the late Famennian, and become extinct at Carboniferous - Devonian boundary.

Animal minds and animal bodies evolved together. When did consciousness emerge and what animals have it? Consciousness has a distinct structure: a predictive, temporalized stream of intentional content. I argue that this structure also solves the biocomputational problem of controlling a complex, active animal body in space. This problem has been solved three times in animal evolution: in vertebrates, in arthropods, and in cephalopod mollusks. This supports the hypothesis that consciousness itself arose near the root of each of these lineages.

Observations on extant mammals suggest that large body mass is selectively advantageous for a terrestrial predator on large herbivores.  Yet, throughout the Cenozoic, some
lineages of terrestrial mammalian predators attained greater maximal body masses than others.  In order to explain this evolutionary pattern, the following biomechanical constraint
on body mass is hypothesized.  The stress, set up in the humerus by the bending moment of the peak ground reaction force at maximal running speed, increased with
increasing body mass within a given lineage of terrestrial mammalian predators, resulting in a decreasing safety factor for the bone, until a predator could no longer attain the
maximal running speed of its smaller relatives.  The selective disadvantage of reduced maximal running speed prevented further increase of body mass within the lineage.
  This hypothesis is tested by examining the scaling of humeral dimensions and estimating maximal body masses in several lineages of terrestrial mammalian predators.  Among lineages with otherwise similar postcranial skeletons, those with the more robust humeri at a given body mass attained the greater maximal body masses.  Lineages with the longer deltoid ridges/deltopectoral crests of the humeri and/or the more distally located deltoid scars (suggesting the more distal insertions of the humeral flexors) at a given body mass also attained the greater maximal body masses.  These results support the existence of the proposed biomechanical constraint, although paleoecological data suggest that some lineages of terrestrial mammalian predators failed to reach the limits, imposed by this constraint, because of the small size of available prey.

[AMAZON LINK BELOW TO BOOK ITSELF -- TOC and book summary in downloadable .doc]      Our instincts—for food, sex, or territorial protection— evolved for life on the savannah 10,000 years ago, not in today’s world of densely populated cities, technological innovations, and pollution. We now have access to a glut of larger-than-life objects, from candy to pornography to atomic weapons—that gratify these gut instincts with often-dangerous results. Animal biologists coined the term “supernormal stimuli” to describe imitations that appeal to primitive instincts and exert a stronger pull than real things, such as soccer balls that geese prefer over eggs. Evolutionary psychologist Deirdre Barrett applies this concept to the alarming disconnect between human instinct and our created environment, demonstrating how supernormal stimuli are a major cause of today’s most pressing problems, including obesity and war. However, Barrett does more than show how unfettered instincts fuel dangerous excesses. She also reminds us that by exercising self-control we can rein them in, potentially saving ourselves and civilization.

A new, consciousness-first scientific paradigm, incorporating Supreme Consciousness, Cosmic Mind and subtle sub-atomic cosmic intelligence agents called microvita, can replace the present materialist paradigm. The new paradigm can provide new insights into the origin and nature of living beings and the observed upward evolutionary trend of life in the universe. In the new paradigm, a Cosmic Cycle of Creation starts from unexpressed infinite Supreme Consciousness and creates a Cosmic Mind and within it the universe containing matter, individual living beings, and human beings with developed minds. Each human mind ultimately completes its Cosmic Cycle by finally merging with unexpressed infinite Supreme Consciousness to spiritually fulfill the goal of human life, according to spiritual guru Prabhat Ranjan Sarkar. According to P. R. Sarkar, life is the “ceaseless fight to restore an unstable equilibrium.” Prominent in different phases of the Cosmic Cycle are the actions of microvita—subtle sub-atomic living beings emanated from the Cosmic Mind, that act as evolutionary cosmic intelligence agents. They move the Cosmic Cycle forward at every step, starting within the formation of fundamental physical particles from microvita. Microvita produce the anti-entropic or upward evolutionary trend of the universe that is currently unexplained. This upward evolutionary trend continues inexorably despite the current laws of physics, especially the second law of thermodynamics, which predicts that the universe as a whole is continually moving from a lower to higher state of entropy or disorder. Microvita participate in upward evolutionary processes from the formation of subatomic particles and atoms, to producing complex biochemical molecules life and minds, to forming new species including human beings, causing and curing diseases, to helping human civilization to advance, and to composing Divine Grace that helps human beings complete their spiritual journey. Scientific research on microvita is urgently needed at all levels, to the discover the natural laws that describe all these actions of microvita, so that many urgent problems facing humanity today can be solved in ways that are beneficial to all.

Leopard remains are rare in the European fossil record, probably a consequence of its solitary and elusive habits. Equi, dating back to Marine Isotope Stage 3 (MIS3), represents a rich and outstanding exception. Historical excavations (from 1911 to about 1917) at Equi allowed  more than 200 remains to be recovered of this large felid, a sample attesting the richest leopard-bearing site in the Pleistocene of Europe. The Equi site testifies the survival of a prosperous leopard population in northwestern Italy (the Apuan Alps area) during the pre Last Glacial Maximum Late Pleistocene. Almost all skeletal elements are represented in the collection (except ribs, and most of axial skeleton). At Equi, leopard is represented by both young and adult animals  and, up to now, it seems the first and unique Pleistocene evidence of cave usage for cubs raised in Europe.
This study focuses on the whole record of leopard from Equi, housed in the Museum of Natural History of Florence, and is aimed to analyze the taphonomical assemblage, to provide an anatomical description of the remains and the comparison to the European evidences. Moreover, we infer the paleoecology of leopards, and their relationships with other large carnivores from the Equi guild (Ursus spelaeus, Canis lupus, and Panthera leo spelaea). The site was probably an occasional large carnivores den, used over time by different large carnivore taxa, perhaps in different seasons or times (mutual avoiding).
Our morphological analysis allows us to recognize sexual dimorphic characters in the cranium, and a large morphological variability in body size.

An intriguing unanswered question about the evolution of bilateral animals with internal skeletons is how an internal skeleton evolved in the first place. Computational modeling of the development of bilateral symmetric organisms suggests an answer to this question. Our hypothesis is that an internal skeleton may have evolved from a bilaterally symmetric ancestor with an external skeleton. By growing the organism inside-out an external skeleton becomes an internal skeleton. Our hypothesis is supported by a computational theory of bilateral symmetry that allows us to model and simulate this process. Inside-out development is achieved by an orientation switch. Given the development of two bilateral founder cells that generate a bilateral organism, a mutation that reverses the internal mirror orientation of those bilateral founder cells leads to inside-out development. The new orientation is epigenetically inherited by all progeny. A key insight is that each cell contained in the newly...

A computational theory and model of the ontogeny and development of bilateral symmetry in multicellular organisms is presented. Understanding the origin and evolution of bilateral organisms requires an understanding of how bilateral symmetry develops, starting from a single cell. Bilateral symmetric growth of a multicellular organism from a single starter cell is explained as resulting from the opposite handedness and orientation along one axis in two daughter founder cells that are in equivalent developmental control network states. Several methods of establishing the initial orientation of the daughter cells (including oriented cell division and cell signaling) are discussed. The orientation states of the daughter cells are epigenetically inherited by their progeny. This results in mirror development with the two founding daughter cells generating complementary mirror image multicellular morphologies. The end product is a bilateral symmetric organism. The theory gives a unified ex...

High-speed, biplanar X-ray motion analysis, X-ray reconstruction of moving morphology (XROMM) and morphological studies have led to the identification of those traits which are considered to be crucial for the evolution of arboreal locomotion in chameleons. The loss of the extensive lateral undulation typical of reptiles needs to be compensated by high mobility in the shoulder girdle and a clear functional regionalization of the trunk. Large limb excursion angles provide a compliant gait and are made possible by a functional parasagittalization of fore-and hind limbs, at least temporarily. All these evolutionary novelties parallel very similar modifications in the evolution of the locomotor apparatus in therian mammals. We propose that the convergent ''invention'' of dynamic stability and a compliant gait seem to be responsible for the locomotor similarities between chameleons and mammals.

The hypothesis that giant short-faced bears of the genera Agriotherium and Arctodus were primarily carnivorous and preyed on large terrestrial mammals is examined.  It is argued that the shape and wear pattern of the cheek teeth and the presence of the premasseteric fossa on the mandible in these two ursids suggest a large amount of plant material in their diet.  Likewise, the absence of adaptations for either ambush or pursuit predation in their skull and postcranial skeleton suggest that they did not
prey on large terrestrial mammals.  Further support for this conclusion is provided by a comparison of the dental and skeletal morphology of Agriotherium and Arctodus to that of Hemicyon ursinus, an extinct ursid widely accepted to have been a predaceous carnivore.  However, it is also argued that the giant short-faced bears included a large amount of animal material in their diets, which was obtained by scavenging.

Many of the 'myths' of direct ancestors of 'all hominids' or of Homo or of H. sapiens and age of these 'ancestors' are shown to be 'false' or based on poor character analyses and/or suboptimal classifications and/or inconsequent choices of names of taxa. Ernst Mayr's devastating influence since 1950 on naming fossil hominids and therefore on comprehending their diversity is obvious. Recently, that is since mid 1990s, many more new taxa of fossil hominids have been found and named, and this has produced a much better appreciation of the prehistoric diversity, and has questioned and put into doubt, if not outright refuted, many of the traditional, often too simplified and adaptationistic scenarios (or 'just-so stories') about human evolution as evidenced by 'direct fossil ancestors'. The most famous of these, 'Lucy', is here named Afaranthropus (n. gen.) antiquus (Ferguson, 1984).

Sauropod (or, more correctly, eusauropod) dinosaurs are highly distinctive, not only in their overall body form, but also in respect to many details of their anatomy. In comparison with basal dinosaurs, typical sauropods are characterized by small skulls, elongate necks, massive bodies, and an obligatory quadrupedal stance with elongate forelimbs and straight limbs in general. Tracing the anatomical changes that led to this distinctive body plan through sauropodomorph evolution is problematic as a result of the incompleteness of many basal taxa and phylogenetic uncertainty at the base of the clade. The decrease in skull size in sauropodomorphs seems to be abrupt at the base of the clade, but it is even more pronounced toward sauropods. Major changes in the sauropod skull are a relative shortening and broadening of the snout and an enlargement and retraction of the nares. Although the ultimate causes for these evolutionary changes are certainly manifold, most if not all of them seem to be related to the ecological and biomechanical requirements of the transition from a carnivorous to an herbivorous lifestyle, in which the skull is
mainly used as a cropping device. A relatively elongate neck seems to be ancestral for sauropodomorphs, but the neck is further elongated on the lineage toward sauropods, especially by incorporation of two additional vertebrae at the base of Sauropoda. The relatively simple structure of the cervical vertebrae in basal sauropodomorphs might be a secondary reduction relative to basal saurischians as a result of changes in neck biomechanics in connection with the reduction of the size of the skull. Thus, the more complicated structure of sauropod cervicals probably reflects changing biomechanical requirements in connection with an elongation of the neck and
an increase in body size, as does the opisthocoelous structure of the cervical vertebral centra. Limb evolution in sauropodomorphs is dominated by adaptations toward increasing body size and thus graviportality, with the limbs getting straighter and the distal limb segments relatively shorter. Body size increase in sauropodomorphs seems to have been rapid but even-paced, with the ancestral body size of the clade being in the 0–10 kg category, and the ancestral body size for sauropods probably being in the 1,000–10,000 kg category.

Giant bear-dogs of the genera Amphicyon and Ischyrocyon (Carnivora, Amphicyonidae, Amphicyoninae) were the largest
carnivorans in North America during middle and late Miocene (17.5–8.8 Mya) with a dental and skeletal morphology that combined features found in living Ursidae, Canidae, and Felidae.  This study tests previously proposed models of diet and hunting behaviour of these extinct carnivorans.  Relative grinding area (RGA) of lower molars and wear pattern on upper molars suggest that bear-dogs were carnivorous.  Amphicyon and Ischyrocyon possessed skeletal features of both ambush (short distal limb segments) and pursuit (caudally bent olecranon process of ulna) living predators.  Therefore, bear-dogs probably pursued their prey (mediportal ungulates) for a longer distance but at a slower speed than do living ambush predators.  Upon catching up to its prey a bear-dog probably seized it with powerfully muscled forelimbs and killed it by tearing into its ribcage or neck with canines set in a narrow rostrum.

The late Cisuralian (Artinskian–Kungurian) is a key time interval for Permian tetrapod evolution. In all the main low-latitude Pangean sites, the fossil footprint record clearly shows a diversification and dispersal of non-synapsid amniote tracks compared to the early Cisuralian (Asselian– Sakmarian). However, data on latest Cisuralian (i.e. late Kungurian) sites are quite fragmentary. A new ichnotaxo-nomic study was carried out in the central part of the Oro-bic Basin, where the highly-fossiliferous Pizzo del Diavolo formation crops out and can potentially cover this gap in knowledge. The following tetrapod ichnogenera were identi-Varanopus; they can be attributed to seymouriamorph and temnospondyl amphibians; pelycosaur synapsids; and diapsid, parareptile and captorhinid reptiles. Dimetropus and Merifontichnus are identified for the first time in the Permian of Italy. The ichnoassociation, in agreement with the radio-metric dating of the underlying Cabianca formation, suggests a late Kungurian (latest Cisuralian) age for the Pizzo del Diavolo formation. It includes the youngest and most diverse non-synapsid amniote ichnofauna of the Cisuralian with five different ichnogenera and possibly six ichnospecies, and thus constitutes a key area for the study of eureptile and pararep-tile dispersal at low latitudes of Pangaea in the time span that immediately pre-dates the first therapsid synapsid radiation .

Biological reconstruction of ape and human (hominoid) evolution, mostly based on comparative, fossil, paleo-environmental and DNA evidence.

Schematically:

(I) arboreal to aquarboreal:
The evolution from monkey to ape body-plan is best explained by a transition from tree-dwelling to living in flooded forests (Mio-Pliocene).

(II) aquarboreal to littoral:
The evolution from ape/australopith to Homo body-plan can mostly be explained by a transition to a coastal and waterside lifestyle during the Ice Ages (early-Pleistocene dispersal along African and Eurasian coasts).

Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate the evolutionary history of parvipelvian ichthyosaurs via phylogenetic and cladogenesis rate analyses. Malawania represents a basal grade in thunnosaurian evolution that arose during a major Late Triassic radiation event and was previously thought to have gone extinct during the Early Jurassic. Its pectoral morphology appears surprisingly archaic, retaining a forefin architecture similar to that of its Early Jurassic relatives. After the initial latest Triassic radiation of early thunnosaurians, two subsequent large radiations produced lineages with Cretaceous representatives, but...

A new Anseriformes, Conflicto antarcticus gen. et sp. nov., represented by associated bones of a single individual,
from the early Palaeocene of Antarctica is described. The new taxon is unlike any other known member of the order.
Conflicto antarcticus is a medium-sized (2 kg) stem anseriform. The forelimb and pectoral girdle bones suggest that
it was a flying bird, and the bones of the hindlimb show that it had elongated legs. The os quadratum represents a
unique combination of features; some are similar to the features of the ancestral quadrate for galloanserines and some
are similar to Anseriformes, but features such as the presence of three foramina are exclusive among Neornithes.
The incisura or foramen nervi suracoracoidei is absent in C. antarcticus, as in most anatids and all Galliformes.
Phylogenetic analysis shows that C. antarcticus + Anatalavis oxfordi is the most basal stem Anseriformes clade. This
implies that the duck-type beak must have developed at an early stage of anseriform evolution. Conflicto antarcticus
represents one (and possibly the most) substantial record of a non-marine Palaeocene bird from the Southern
Hemisphere and supports the hypothesis that Neognathae had already diversified in the earliest Palaeocene.

Els vertebrats del Triàsic a Catalunya es concentren en pocs jaciments, principalment dels sectors del Montseny i de Montral-Alcover (Tarragona). Al massís del Montseny els afloraments tenen una edat de Triàsic mitjà. En fàcies Buntsandstein i Muschelkalk s’han recuperat restes de peixos, amfibis i rèptils. A l’area del Pla de la Calma i zones limítrofes els jaciments adquireixen un valor més alt: se n’han documentat abundants  petjades (icnites) de tetràpodes, restes fòssils de flora i invertebrats i una important localitat que ha aportat centenars de restes assignades, majoritàriament a un amfibi de tipus capitosàurid, a més d’altres amfibis i rèptils. Des de l’any 2008, s’han reprès les actuacions paleontològiques al Montseny (amb noves excavacions i prospeccions) en el marc d’un projecte d’investigació dels vertebrats del Triàsic de Catalunya.

Body size changes of Bison and mortality age structure data document the effects of climate-driven environmental change and human hunting pressure on large mammals in North America. Morphometric and mortality data are drawn from 58 archaeological and 9 paleontological localities dating between 37,000 and 250 calBP. Proxy information on body size is based on measurements recorded on 901 adult calcanei (os calcis) and 1026 humeri. In addition, published mortality profiles from 24 archaeological faunal assemblages spanning the last 14,000 years were used to approximate the age structure of bison populations. These results suggest that dramatic diminution in bison body size occurred in several short bursts, rather than a continuous gradual decline. These periods of rapid size reduction correlate with times of ecological reorganization, when aridity-driven changes in grasslands decreased forage quality and availability. Mortality age data indicate that the decrease in body size occurred in a context where there was no evidence for a progressively severe juvenile bias in bison populations. Overall, it appears that the changes in body size were a reaction to environmental conditions rather than the result of human predation pressure.

Two new Early Devonian eagaleapids from Qujing, Yunnan in South China are described here. One is Nochlaspis meandrine gen. et sp. nov., collected from the lower part of Xishancun Fofrriajion (early Early Devonian), the other Pterogonaspis yuhaii gen. et sp. nov. from Xujiachong Formation (late Early Devonian). Nochelaspis, the largest eugaleaspid so far described, is an element of the Early Vertebrate fauna in Xishancun Formation (Zhu, 1991), which includes polybranchiaspids, paleoniscoids, crossopterygian, arthrodire, antiarchs, petalichthyids (Zhu, dissertation; in preparation). Pterogonaspis, the huananaspid-like eugaleaspid, occurred in the same bed with Eugaleaspis xujiachongensis, Sanchaspis magalarostra, yunnanolepids and plant remains. Both genera throw lights on the phylogeny of eugaleaspids and galeaspids. Eugaleaspids are assumed to be a monophyletic galeaspid group by (1) the eugaleaspid pattern lateral line system and (2) the longitudinal oval median dorsal opening (if the median dorsal opening of Nanpanaspis is due to the parallelism). By now, there have been 7 genera including 12 species of eugaleaspids described, ranging from Middle Silurian to Early Devonian (Fig. 3). The character analysis of eugaleaspids has been done in view of Cladistics. With the principle of parsimony, a new testable cladogram is established (Fig. 5).

Here we present a set of RNA-based probes for whole mitochondrial genome in-solution enrichment, targeting a diversity of mammalian mitogenomes. This probes set was designed from 7 mammalian orders and tested to determine the utility for enriching degraded DNA. We generated 63 mitogenomes representing five orders and 22 genera of mammals that yielded varying coverage ranging from 0 to > 5,400X. Based on a threshold of 70% mitogenome recovery and at least 10X average coverage, 32 or 51% of samples were considered successful. The estimated sequence divergence of samples from the probe sequences used to construct the array ranged up to 20%. Sample type was more predictive of mitogenome recovery than sample age. The proportion of reads from each individual in multiplexed enrichments was highly skewed, with each pool having one sample that yielded a majority of the reads.

The vertebrate record at the Ziegler Reservoir fossil site (ZRFS) near Snowmass Village, Colorado ranges from 140 to 77 ka, spanning all of Marine Oxygen Isotope Stage (MIS) 5. The site contains at least 52 taxa of macro-and microvertebrates, including one fish, three amphibian, four reptile, ten bird, and 34 mammal taxa. The most common vertebrate is Ambystoma tigrinum (tiger salamander), which is represented by N 22,000 elements representing the entire life cycle. The mastodon, Mammut americanum, is the most common mammal, and is documented by N 1800 skeletal elements making the ZRFS one of the largest accumulations of proboscidean remains in North America. Faunas at the ZRFS can be divided into two groups, a lake-margin group dating tõ 140-100 ka that is dominated by woodland taxa, and a lake-center group dating to~87-77 ka characterized by taxa favoring more open conditions. The change in faunal assemblages occurred between MIS 5c and 5a (vertebrates were absent from MIS 5b deposits), which were times of significant environmental change at the ZRFS. Furthermore, the ZRFS provides a well-dated occurrence of the extinct Bison latifrons, which has implications for the timing of the Rancholabrean Mammal Age in the region. ). However, prior to the discovery of the ZRFS, only three fragmentary records of Mammut americanum were known from Colorado (McDonald et al., 2010), none of which were located at high elevation.