2014 in paleontology
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, burrows, cast-off parts, fossilised feces and chemical residues; because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2014. Specimens of Micromelerpeton crederni with abnormalities in their limbs interpreted as a result of limb regeneration are described by Fröbisch and Witzmann. Redescription of Mahavisaurus dentatus and Lyrosaurus australis and a study on the phylogenetic relationships of the rhytidosteids is published by Maganuco, Pasini & Auditore; the humerus bone of a large calyptocephalellid anuran one of the largest fossil anurans known to date, is described by Otero et al. from the Eocene of Chile. Anatomy and phylogenetic relationships of Cretaceous ophthalmosaurids Simbirskiasaurus birjukovi and Pervushovisaurus bannovkensis are reevaluated by Fischer et al..
Redescription of the rediscovered holotype of the Jurassic turtle Plesiochelys etalloni is published by Anquetin, Deschamps & Claude. A redescription of Tasmaniosaurus triassicus is published by Ezcurra. A revision of anatomy and phylogenetic relationships of the archosauriform Dorosuchus neoetus is published by Sookias et al.. A revision of putative euparkeriids from the Triassic of China is published by Sookias et al.. A study of anatomy and phylogenetic relationships of Gracilisuchus stipanicicorum, Turfanosuchus dabanensis and Yonghesuchus sangbiensis is published by Butler et al.. A study on the impact of sea level variations and sea surface temperatures on the evolution of marine crocodylomorphs is published by Martin et al.. A study of jaw mechanism and dental function in heterodont crocodyliforms is published by Ősi. A study on the types of serration in the teeth of members of the genus Machimosaurus is published by Young et al.. The atoposaurid crocodyliform genus Alligatorellus is revised by Mannion.
A study on the patterns of body size evolution in dinosaurs is published by Benson et al.. A study of size changes and rates of anatomical innovation in the theropod lineage ancestral to birds is published by Lee et al.. A study of evolution of body size and forelimb length in birds and nov-avian coelurosaurian theropods is published by Puttick and Benton. A phylogenetic analysis of bird and non-avian coelurosaurian theropod relationships and a study of rates of morphological evolution and changes in morphological disparity across the dinosaur-bird transition is published by Brusatte et al.. A description of abelisaurid teeth from the Late Jurassic Lourinhã Formation of Portugal and a phylogenetic analysis of theropod relationships based on dental characters is published by Hendrickx and Mateus. A study of theropod diversity in the Cretaceous of Tunisia is published by Fanti et al.. A juvenile specimen of Megaraptor namunhuaiquii is described by Porfiri et al.. A study of European fossil record of Ornithomimosauria is published by Allain et al..
A study on the morphological variability and function of manual claws in theropod dinosaurs in therizinosaurs, is published by Lautenschlager. A study of flight ability in some non-avian paravian theropods is published by Sorkin. "Saurornitholestes" robustus thought to be a dromaeosaurid, is reinterpreted as a troodontid by Evans et al.. A well-preserved specimen of Microraptor zhaoianus is described by Pei et al.. A study of anatomy and phylogenetic relationships of Antetonitrus ingenipes is published by McPhee et al.. A study on the differences in skull anatomy of Diplodocus and Camarasaurus, on their implications for inferring possible niche partitioning between Late Jurassic sauropod taxa known from the Morrison Formation, is published by Button, Rayfield & Barrett. Fragmentary partial skeleton of a small sauropod belonging to the genus Haplocanthosaurus collected from the Rocky Mountains of central Colorado is described by Foster & Wedel; the purported size of the holotype vertebra of Amphicoelias fragillimus is reevaluated by Woodruff and Foster.
A study of phylogenetic relationships of Lourinhasaurus alenquerensis is published by Mocho, Royo-Torres and Ortega. A study of anatomy and phylogenetic relationships of Aragosaurus ischiaticus is published by Royo-Torres et al.. A study of titanosaur osteoderms from the Upper Cretaceous Lo Hueco site in Cuenca, Spain is published by Vidal and Sanz. A study of species richness of South American titanosaur assemblages during the Late Cretaceous is published by Vieira et al.. A study of the effect of intervertebral cartilage on neck posture of sauropod dinosaurs is published by Taylor. A study of the dentition of Manidens condorensis is published by Becerra et al.. A study of the postcranial anatomy of Heterodontosaurus tucki is published by Galton. A study of the impact of osteoderm placement on the centre of mass of stegosaurs is published by Mallison. A study of Early Cretaceous Spanish iguanodont ornithopod diversity and a description of new remains referrable to Delapparentia is published by Gasca and Moreno-Azanza.
A specimen of Edmontosaurus regalis with remains of a soft-tissue cranial crest is described by Bell et al.. A juvenile specimen of Edmont
Unaysauridae is a family of basal sauropodomorphs from the Late Triassic of India and Brazil. Unaysauridae was defined by Müller et al. as the most inclusive clade including Unaysaurus tolentinoi, but not Plateosaurus engelhardti nor Saltasaurus loricatus. Members of Unaysauridae are diagnosed by a expanded cranial part of the medial condyle of the astragalus, as well as a promaxillary fenestra. Unaysauridae is sister to Plateosauria, more derived than Nambalia, Thecodontosaurus ISI R277, Efraasia. Unaysaurus and Jaklapallisaurus had been assigned to Plateosauridae by prior authors
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, snakes, lizards and their extinct relatives. The study of these traditional reptile orders combined with that of modern amphibians, is called herpetology; because some reptiles are more related to birds than they are to other reptiles, the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping or clade. For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living Diapsids; the earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became adapted to life on dry land. Some early examples include Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs and sauropods, as well as many species of theropods, including troodontids, dromaeosaurids and abelisaurids, along with many Crocodyliformes, squamates.
Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica. Several living subgroups are recognized: Testudines, 350 species. Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades – the fetus develops within the mother, contained in a placenta rather than an eggshell; as amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm to the saltwater crocodile, Crocodylus porosus, which can reach 6 m in length and weigh over 1,000 kg.
In the 13th century the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, assorted amphibians, worms", as recorded by Vincent of Beauvais in his Mirror of Nature. In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his Systema Naturæ; the terms "reptile" and "amphibian" were interchangeable, "reptile" being preferred by the French. Josephus Nicolaus Laurenti was the first to formally use the term "Reptilia" for an expanded selection of reptiles and amphibians similar to that of Linnaeus. Today, the two groups are still treated under the same heading as herptiles, it was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, Pierre André Latreille erected the class Batracia for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians and mammals.
The British anatomist Thomas Henry Huxley made Latreille's definition popular and, together with Richard Owen, expanded Reptilia to include the various fossil "antediluvian monsters", including dinosaurs and the mammal-like Dicynodon he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1863, Huxley grouped the vertebrates into mammals and ichthyoids, he subsequently proposed the names of Ichthyopsida for the latter two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, that reptiles and mammals were united by the amniotic egg; the terms "Sauropsida" and "Theropsida" were used again in 1916 by E. S. Goodrich to distinguish between lizards and their relatives on the one hand and mammals and their extinct relatives on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, other features, such as the structure of the forebrain.
According to Goodrich, both lineages evolved from an earlier stem group, Protosauria in which he included some animals today considered reptile-like amphibians, as well as early reptiles. In 1956, D. M. S. Watson observed that the first two groups diverged early in reptilian history, so he divided Goodrich's Protosauria between them, he reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included Procolophonia, Millerosauria, Squamata, Rhynchocephalia
Bagualosaurus is a genus of sauropodomorph dinosaur from the Santa Maria Formation of Brazil, dating to around 230 million years ago in the Carnian of the Late Triassic. It includes one species, Bagualosaurus agudoensis. In 2007, in a ravine at the outcrop of Janner, near Agudo in Rio Grande do Sul, a sauropodomorph skeleton was excavated, it was removed in a single block of stone. For five years it remained unprepared in the collection of the Laboratório de Paleovertebrados da Universidade Federal do Rio Grande do Sul, curated by Cesar Leandro Schultz. In 2012, Flávio Augusto Pretto began to study the specimen. In 2018, Max Cardoso Langer and Schultz named and described the type species Bagualosaurus agudoensis; the generic name is derived from bagual, "strongly built fellow" in the dialect of Rio Grande do Sul, in reference to the strong hindlimbs. The specific name refers to the provenance from Agudo; the holotype, UFRGS-PV-1099-T, has been found in a layer of red mudstone of the Candelária sequence dating from the Carnian.
It consists of a partial skeleton with skull. It contains the lower parts of the skull, the lower jaws, nine back vertebrae, three sacral vertebrae, two tail vertebrae, belly ribs, both ilia, the right pubic bone, both thighbones, both shinbones, both calfbones, the left foot; the skeleton was articulated but has been damaged by erosion. It was found on its back with a rare position for archosaurian fossils. Bagualosaurus was a modest-sized basal sauropodomorph, measuring 2.5 metres in length that, based on its teeth, was a herbivore. Features of its skull and dental structure are similar to Norian sauropodomophs such as Pantydraco and Plateosaurus. However, its post-cranial skeleton resembles earlier forms, it is somewhat smaller than Norian sauropodomorphs, yet larger than other sauropodomorphs of its time, suggesting that it is transitional between the sauropodomorphs of its time and their Norian descendants. 2018 in paleontology
In zoological nomenclature, a type species is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e. the species that contains the biological type specimen. A similar concept is used for suprageneric groups called a type genus. In botanical nomenclature, these terms have no formal standing under the code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen, the type of a species name; the species name that has that type can be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, some higher-rank names based on genus names, have such types. In bacteriology, a type species is assigned for each genus; every named genus or subgenus in zoology, whether or not recognized as valid, is theoretically associated with a type species. In practice, there is a backlog of untypified names defined in older publications when it was not required to specify a type.
A type species is both a concept and a practical system, used in the classification and nomenclature of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species; the term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature, which defines a type species as the name-bearing type of the name of a genus or subgenus. In the Glossary, type species is defined as The nominal species, the name-bearing type of a nominal genus or subgenus; the type species permanently attaches a formal name to a genus by providing just one species within that genus to which the genus name is permanently linked. The species name in turn is fixed, to a type specimen. For example, the type species for the land snail genus Monacha is Helix cartusiana, the name under which the species was first described, known as Monacha cartusiana when placed in the genus Monacha.
That genus is placed within the family Hygromiidae. The type genus for that family is the genus Hygromia; the concept of the type species in zoology was introduced by Pierre André Latreille. The International Code of Zoological Nomenclature states that the original name of the type species should always be cited, it gives an example in Article 67.1. Astacus marinus Fabricius, 1775 was designated as the type species of the genus Homarus, thus giving it the name Homarus marinus. However, the type species of Homarus should always be cited using its original name, i.e. Astacus marinus Fabricius, 1775. Although the International Code of Nomenclature for algae and plants does not contain the same explicit statement, examples make it clear that the original name is used, so that the "type species" of a genus name need not have a name within that genus, thus in Article 10, Ex. 3, the type of the genus name Elodes is quoted as the type of the species name Hypericum aegypticum, not as the type of the species name Elodes aegyptica.
Glossary of scientific naming Genetypes – genetic sequence data from type specimens. Holotype Paratype Principle of Typification Type Type genus
In phylogenetics, basal is the direction of the base of a rooted phylogenetic tree or cladogram. The term may be more applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root; each node in the tree corresponds to a clade. The terms deep-branching or early-branching are similar in meaning. While there must always be two or more basal clades sprouting from the root of every cladogram, those clades may differ in taxonomic rank and/or species diversity. If C is a basal clade within D that has the lowest rank of all basal clades within D, C may be described as the basal taxon of that rank within D. Greater diversification may be associated with more evolutionary innovation, but ancestral characters should not be imputed to the members of a less species-rich basal clade without additional evidence, as there can be no assurance such an assumption is valid. In general, clade A is more basal than clade B if B is a subgroup of the sister group of A.
Within large groups, "basal" may be used loosely to mean'closer to the root than the great majority of', in this context terminology such as "very basal" may arise. A'core clade' is a clade representing all but the basal clade of lowest rank within a larger clade. A basal group in the stricter sense forms a sister group to the rest of the larger clade, as in the following case: While it is easy to identify a basal clade in such a cladogram, the appropriateness of such an identification is dependent on the accuracy and completeness of the diagram, it is assumed in this example that the terminal branches of the cladogram depict all the extant taxa of a given rank within the clade. Additionally, this qualification does not ensure. In phylogenetics, the term basal can be objectively applied to clades of organisms, but tends to be applied selectively and more controversially to groups or lineages thought to possess ancestral characters, or to such presumed ancestral traits themselves. In describing characters, "ancestral" or "plesiomorphic" are preferred to "basal" or "primitive", the latter of which may carry false connotations of inferiority or a lack of complexity.
Despite the ubiquity of the usage of basal, some systematists believe its application to extant groups is unnecessary and misleading. The term is more applied when one branch is less diverse than another branch; the term may be equivocal in that it refers to the direction of the root of the tree, which represents a hypothetical ancestor. An extant basal group may or may not resemble the last common ancestor of a larger clade to a greater degree than other groups, is separated from that ancestor by the same amount of time as all other extant groups. However, there are cases where the unsually small size of a sister group does indeed correlate with an unusual number of ancestral traits, as in Amborella. Other famous examples of this phenomenon are the oviparous reproduction and nipple-less lactation of monotremes, a basal clade of mammals with just five species, the archaic anatomy of the tuatara, a basal clade of lepidosaurian with a single species; the flowering plant family Amborellaceae, restricted to New Caledonia in the southwestern Pacific, is a basal clade of extant angiosperms, consisting of the most basal species, genus and order within the group.
The traits of Amborella trichopoda are regarded as providing significant insight into the evolution of flowering plants. However, those traits are a mix of archaic and apomorphic features that have only been sorted out via comparison with other angiosperms and their positions within the phylogenetic tree. Within the primate family Hominidae, gorillas are a sister group to common chimpanzees and humans; these five species form the subfamily Homininae, of which Gorilla is the basal genus. However, if the analysis is not restricted to genera, the Homo plus Pan clade is basal. Moreover, orangutans are a sister group to Homininae and are the basal genus in the family as a whole. Subfamilies Homininae and Ponginae are both basal within Hominidae, but given that there are no nonbasal subfamilies in the cladogram it is unlikely the term would be applied to either. In general, a statement to the effect that one group is basal, or branches off first, within another group may not make sense unless the appropriate taxonomic level is specified.
If that level cannot be specified a more detailed description of the relevant sister groups may be needed. In this example, orangutans differ from the other genera in their Asian range; this fact plus their basal status provides a hint that the most recent common ancestor of extant great apes may have been Eurasian, a suggestion, consistent with other evidence. Orangutans differ from African apes in their more arboreal lifestyle, a
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma