The phylogenetic position of the Tyrannosauridae: implications for theropod systematics

1994 ◽  
Vol 68 (5) ◽  
pp. 1100-1117 ◽  
Author(s):  
Thomas R. Holtz

Tyrannosaurids are a well-supported clade of very large predatory dinosaurs of Late Cretaceous Asiamerica. Traditional dinosaurian systematics place these animals within the infraorder Carnosauria with the other large theropods (allosaurids, megalosaurids). A new cladistic analysis indicates that the tyrannosaurs were in fact derived members of the Coelurosauria, a group of otherwise small theropods. Despite certain gross cranial similarities with the large predators of the Jurassic and Early Cretaceous, the Late Cretaceous tyrannosaurids are shown to be the sister group to ornithomimids and troodontids, which share a derived condition of the metatarsus. This clade is found to be nested within Maniraptora, which is a more inclusive taxon than previously recognized. The atrophied carpal structure found in tyrannosaurids and ornithomimids is derived from a maniraptoran condition with a large semilunate carpal, rather than from the plesiomorphic theropod morphology.The taxa “Carnosauria” and “Deinonychosauria” (Dromaeosauridae plus Troodontidae) are shown to be polyphyletic, and the Late Jurassic African form Elaphrosaurus is found to be the sister taxon to Abelisauridae rather than a primitive ornithomimosaur. Purported allosaurid-tyrannosaurid synapomorphies are seen to be largely size-related, present in the larger members of both clades, but absent in smaller members of the Tyrannosauridae. The remaining giant tetanurine theropods (Megalosaurus and Torvosaurus) were found to be progressively distant outgroups to an allosaurid-coelurosaur clade. The inclusion of the Tyrannosauridae within Maniraptora suggests a major adaptive radiation of coelurosaurs within Cretaceous Asiamerica comparable to contemporaneous radiations in various herbivorous dinosaurian clades.

Zootaxa ◽  
2008 ◽  
Vol 1863 (1) ◽  
pp. 1 ◽  
Author(s):  
PATRICK S. DRUCKENMILLER ◽  
ANTHONY P. RUSSELL

Leptocleidus Andrews, 1922 is a poorly known plesiosaur genus from Lower Cretaceous successions of the UK, South Africa, and Australia. Historically, there has been little consensus regarding its phylogenetic position within Plesiosauria, largely because of its seemingly aberrant combination of a relatively small skull and short neck. As a result, a diverse array of potential sister groups have been posited for Leptocleidus, including long-necked Cretaceous elasmosaurids, Early Jurassic “rhomaleosaurs”, and Middle to Late Jurassic pliosaurids. A cladistic analysis including Leptocleidus, and a new, apparently morphologically similar specimen from Alberta, TMP 94.122.01, was undertaken to assess their phylogenetic position within Plesiosauria. A character-taxon matrix was assembled afresh, consisting of 33 operational taxonomic units sampled broadly among plesiosaurs. 185 cranial and postcranial characters used in plesiosaur phylogenetics were critically reanalyzed, of which 152 were employed in the parsimony analysis. The results indicate a basal dichotomous split into the traditionally recognized pliosauroid and plesiosauroid clades. Nested within Pliosauroidea, a monophyletic Leptocleididae was recovered, consisting of L. superstes Andrews, 1922 and L. capensis (Andrews, 1911a). In contrast to earlier suggestions, Leptocleidus neither clusters with Rhomaleosaurus, which was found to be paraphyletic, nor with large-skulled pliosaurid taxa, such as Simolestes. Rather, a sister group relationship between Cretaceous Polycotylidae and Leptocleididae was recovered, which is here named Leptocleidoidea. Although TMP 94.122.01 is superficially similar to Leptocleidus, several discrete characters of the skull nest this new taxon within Polycotylidae. Compared to other phylogenetic hypotheses of plesiosaurs, these results are more congruent with respect to the stratigraphic distribution of leptocleidoids. A classification for Plesiosauria is presented.


2005 ◽  
Vol 36 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Valerie Schawaroch ◽  
Jeyaraney Kathirithamby ◽  
David Grimaldi

AbstractThe first definitive strepsipteran is reported from the Cretaceous, named Cretostylops engeli, n.gen., n.sp., which is an adult male in amber from the mid-Cretaceous (approximately Cenomanian) of northern Myanmar (Burma). A triungulin from the Late Cretaceous (Campanian, c. 80 myo) of Manitoba, Canada is possibly a strepsipteran. The triungulin is described in detail but its morphology does not conform to any known clade of Recent strepsipterans. Other Cretaceous triungula reported here are in Burmese amber and are probably of the family Rhipiphoridae (Coleoptera), and bizarre (possibly coleopteran) triungula in mid-Cretaceous (Turonian, c. 90 myo) amber from New Jersey, USA. Phylogenetic analysis confirms the primitive position of Cretostylops among families of Strepsiptera, but it is not as primitive as Protoxenos in Eocene Baltic amber. Protoxenos and Cretostylops are still too highly modified to address the controversial relationships of Strepsiptera among insect orders, but the generalized structure of the mandible is inconsistent with the hypothesis that this order is the sister group to Diptera or closely related to Mecopterida. Phylogeny of living and Recent Strepsiptera suggests an origin of the order in the Early Cretaceous or Late Jurassic, which is also inconsistent with this order being a sister group to the much older Diptera.


2021 ◽  
Author(s):  
Ksenia Juravel ◽  
Luis Porras ◽  
Sebastian Hoehna ◽  
Davide Pisani ◽  
Gert Wörheide

An accurate phylogeny of animals is needed to clarify their evolution, ecology, and impact on shaping the biosphere. Although multi-gene alignments of up to several hundred thousand amino acids are nowadays routinely used to test hypotheses of animal relationships, some nodes towards the root of the animal phylogeny are proving hard to resolve. While the relationships of the non-bilaterian lineages, primarily sponges (Porifera) and comb jellies (Ctenophora), have received much attention since more than a decade, controversies about the phylogenetic position of the worm-like bilaterian lineage Xenacoelomorpha and the monophyly of the "Superphylum" Deuterostomia have more recently emerged. Here we independently analyse novel genome gene content and morphological datasets to assess patterns of phylogenetic congruence with previous amino-acid derived phylogenetic hypotheses. Using statistical hypothesis testing, we show that both our datasets very strongly support sponges as the sister group of all the other animals, Xenoacoelomorpha as the sister group of the other Bilateria, and largely support monophyletic Deuterostomia. Based on these results, we conclude that the last common animal ancestor may have been a simple, filter-feeding organism without a nervous system and muscles, while the last common ancestor of Bilateria might have been a small, acoelomate-like worm without a through gut.


2013 ◽  
Vol 27 (1) ◽  
pp. 129
Author(s):  
Edilson Caron ◽  
Cibele S. Ribeiro-Costa ◽  
Alfred F. Newton

Rove beetles of the genus Piestus Gravenhorst, 1806 are commonly captured under the bark of or inside decaying logs from Neotropical forests. Piestus belongs to the subfamily Piestinae, historically an ill-defined dumping-ground for Staphylinidae defined by plesiomorphic characters, but which has gradually been restricted in concept and currently includes only six additional extant genera worldwide. Piestinae in this restricted sense has been considered a probably monophyletic subfamily, but its status and phylogenetic position, as a possible sister-group of Osoriinae within the recently proposed Oxyteline group of staphylinid subfamilies, are uncertain and need confirmation. The main aim of the present study was to provide a morphological cladistic analysis and complete taxonomic revision of Piestus, which, as the type and most speciose genus of Piestinae, is critical for future phylogenetic studies involving the subfamily. In our study, the monophyly of Piestus is established and phylogenetic relationships among its species are proposed based on 70 adult morphological characters. Piestus is supported by 11 synapomorphies and high branch support. All species of Piestus are revised and the genus is redefined. The genus contains 43 species, including 13 species described here for the first time. The previously proposed subgenera Antropiestus Bernhauer, 1917, Eccoptopiestus Scheerpeltz, 1952, Elytropiestus Scheerpeltz, 1952, Lissopiestus Scheerpeltz, 1952, Piestus s. str., Trachypiestus Scheerpeltz, 1952 and Zirophorus Dalman, 1821 have not been confirmed, as they were found to be poly- or paraphyletic, or are here removed from Piestus, and therefore subgenera are not used. The main taxonomic changes are as follows. Lissopiestus, syn. nov. is proposed as new synonym of Eleusis Laporte, 1835 and its species, E. interrupta (Erichson, 1840), comb. rest., is transferred again to that genus. Antropiestus, syn. nov. and Eccoptopiestus, syn. nov. are proposed as new synonyms of Hypotelus Erichson, 1839 and their species, H. laevis (Solsky, 1872), comb. nov. and H. andinus (Bernhauer, 1917), comb. nov., are transferred to Hypotelus. Fourteen new synonymies are proposed (valid species listed first): P. lacordairei Laporte, 1835 = Z. furcatus Sharp, 1887, syn. nov.; P. capricornis Laporte, 1835 = P. frontalis Sharp, 1876, syn. nov.; P. pennicornis Fauvel, 1864 = P. plagiatus Fauvel, 1864, syn. nov.; P. rectus Sharp, 1876, syn. nov.; P. pygialis Fauvel, 1902, syn. nov.; P. surinamensis Bernhauer, 1928, syn. nov.; P. minutus Erichson, 1840 = P. nigrator Fauvel, 1902, syn. nov.; P. sulcatus Gravenhorst, 1806 = P. sanctaecatharinae Bernhauer, 1906, syn. nov.; P. condei Wendeler, 1955, syn. nov.; P. gounellei Fauvel, 1902 = P. wasmanni Fauvel, 1902, syn. nov.; P. mexicanus Laporte, 1835 = P. alternans Sharp, 1887, syn. nov.; P. aper Sharp, 1876 = P. schadei Scheerpeltz, 1952, syn. nov.; P. angularis Fauvel, 1864 = P. crassicornis Sharp, 1887, syn. nov.; H. andinus (Bernhauer, 1917) = P. strigipennis Bernhauer, 1921, syn. nov. One species is revalidated: P. fronticornis (Dalman, 1821), stat. rev., and one synonym is restored: P. penicillatus (Dalman, 1821) = P. erythropus Erichson, 1840, syn. rest. Neotypes are designated for P. lacordairei Laporte, 1835 and Oxytelus bicornis Olivier, 1811, and lectotypes are designated for P. puncticollis Fauvel, 1902, P. capricornis variety muticus Fauvel, 1902, P. zischkai Scheerpeltz, 1951, P. pennicornis Fauvel, 1864, P. plagiatus Fauvel, 1864, P. pygmaeus Laporte, 1835, P. niger Fauvel 1864, P. minutus Erichson, 1840, P. nigratror Fauvel, 1902, P. sulcatus Gravenhorst, 1806, P. sanctaecatharinae Bernhauer, 1906, P. sulcipennis Scheerpeltz, 1952, P. aper Sharp, 1876, P. schadei Scheerpeltz, 1952 and P. andinus Bernhauer, 1917.


1992 ◽  
Vol 335 (1274) ◽  
pp. 207-219 ◽  

Sphenodon has traditionally been regarded as a little changed survivor of the Permo-Triassic thecodont or eosuchian ‘stem reptiles’ but has alternatively been placed in the Lepidosauria as the plesiomorphic or even apomorphic sister-taxon of the squamates. A cladistic analysis of 16 characters from spermatozoal ultrastructure of Sphenodon and other amniotes unequivocally confirms its exceedingly primitive status. The analysis suggests that monotremes are the sister-group of birds; squamates form the sister-group of a bird + monotreme clade while the three sister-groups successively below the bird + monotreme + squa- mate assemblage are the caiman, the tuatara and the outgroup (turtles). The monotreme + bird couplet, supports the concept of the Haemothermia, but can only be regarded heuristically. The usual concept of mammals as a synapsid-derived outgroup of all other extant amniotes is not substantiated spermatologically. All cladistic analyses made, and a separate consideration of apomorphies, indicate that Sphenodon is spermatologically the most primitive amniote, excepting the Chelonia. It is advanced (apomorphic) for the amniotes in only two of the 16 spermatozoal characters considered. A close, sister-group relationship of Sphenodon with squamates is not endorsed.


2003 ◽  
Vol 81 (6) ◽  
pp. 962-970 ◽  
Author(s):  
Darla K Zelenitsky ◽  
Sean P Modesto

A reappraisal of the eggshell of ratites clarifies aspects of its microstructure and ultrastructure. The phylogenetic usefulness of the eggshell data, consisting of discrete characters, is assessed using eggshell characters alone and by adding the eggshell characters to a data matrix from the literature based on skeletal characters. The resultant tree from the eggshell data alone yields Apteryx as the most basal ratite, dinornithids as the sister taxon of a clade of large living ratites, with Casuarius and Dromaius in a sister-group relationship. The combined eggshell and skeletal analysis revealed most groupings within Ratitae that were based on previous cladistic analysis of the skeletal characters alone, but also supports two equally parsimonious topologies: one identifies Dinornithidae and Apteryx as a clade at the base of Ratitae, and the other identifies Apteryx as the sister taxon of a clade consisting of all the other ratites. It is determined that the characteristics used to define the improperly named "ratite morphotype" in the current eggshell parataxonomy are not synapomorphies of the eggshell of Ratitae. An expanded cladistic analysis of the eggshells of avian and non-avian theropods is required to determine the phylogenetic usefulness of the characteristics of the ratite morphotype.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1765 ◽  
Author(s):  
Jiandong Huang ◽  
Xia Wang ◽  
Yuanchao Hu ◽  
Jia Liu ◽  
Jennifer A. Peteya ◽  
...  

Despite the increasing number of exceptional feathered fossils discovered in the Late Jurassic and Cretaceous of northeastern China, representatives of Ornithurae, a clade that includes comparatively-close relatives of crown clade Aves (extant birds) and that clade, are still comparatively rare. Here, we report a new ornithurine speciesChangzuiornis ahgmifrom the Early Cretaceous Jiufotang Formation. The new species shows an extremely elongate rostrum so far unknown in basal ornithurines and changes our understanding of the evolution of aspects of extant avian ecology and cranial evolution. Most of this elongate rostrum inChangzuiornis ahgmiis made up of maxilla, a characteristic not present in the avian crown clade in which most of the rostrum and nearly the entire facial margin is made up by premaxilla. The only other avialans known to exhibit an elongate rostrum with the facial margin comprised primarily of maxilla are derived ornithurines previously placed phylogenetically as among the closest outgroups to the avian crown clade as well as one derived enantiornithine clade. We find that, consistent with a proposed developmental shift in cranial ontogeny late in avialan evolution, that this elongate rostrum is achieved through elongation of the maxilla while the premaxilla remains only a small part of rostral length. Thus, only in Late Cretaceous ornithurine taxa does the premaxilla begin to play a larger role. The rostral and postcranial proportions ofChangzuiornissuggest an ecology not previously reported in Ornithurae; the only other species with an elongate rostrum are two marine Late Cretacous taxa interpreted as showing a derived picivorous diet.


Zootaxa ◽  
2018 ◽  
Vol 4415 (3) ◽  
pp. 452 ◽  
Author(s):  
P. R. PUGH ◽  
C.W. DUNN ◽  
S.H.D. HADDOCK

A new species of calycophoran siphonophore, Tottonophyes enigmatica gen. nov, sp. nov., is described. It has a unique combination of traits, some shared with prayomorphs (including two rounded nectophores) and some with clausophyid diphyomorphs (the nectophores are dissimilar, with one slightly larger and slightly to the anterior of the other, and both possess a somatocyst). Molecular phylogenetic analyses indicate that the new species is the sister group to all other diphyomorphs. A new family, Tottonophyidae, is established for it. Its phylogenetic position and distinct morphology help clarify diphyomorph evolution. The function and homology of the nectophoral canals and somatocyst is also re-examined and further clarification is given to their nomenclature.


2020 ◽  
Author(s):  
Remi J.G. Charton

Our understanding of the Earth’s interior is limited by the access we have of its deep layers, while the knowledge we have of Earth’s evolution is restricted to harvested information from the present state of our planet. We therefore use proxies, physical and numerical models, and observations made on and from the surface of the Earth. The landscape results from a combination of processes operating at the surface and in the subsurface. Thus, if one knows how to read the landscape, one may unfold its geological evolution.In the past decade, numerous studies have documented km-scale upward and downward vertical movements in the continental rifted margins of the Atlantic Ocean and in their hinterlands. These movements, described as exhumation (upward) and subsidence (downward), have been labelled as “unpredicted” and/or “unexpected”. ‘Unpredicted’ because conceptual, physical, and numerical models that we dispose of for the evolution of continental margins do not generally account for these relatively recent observations. ‘Unexpected’ because the km-scale vertical movements occurred when our record of the geological history is insufficient to support them. As yet, the mechanisms responsible for the km-scale vertical movements remain enigmatic.One of the common techniques used by geoscientists to investigate the past kinematics of the continental crust is to couple ‘low-temperature thermochronology’ and ‘time-temperature modelling’. In Morocco alone, over twenty studies were conducted following this approach. The reason behind this abundance of studies and the related enthusiasm of researchers towards Moroccan geology is due to its puzzling landscapes and complex history. In this Thesis, we investigate unconstrained aspects of the km-scale vertical movements that occurred in Morocco and its surroundings (Canary Islands, Algeria, Mali, and Mauritania). The transition area between generally subsiding domains and mostly exhuming domains, yet poorly understood, is discussed via the evolution of a profile, running across the rifted continental margin (chapter 2). Low-temperature thermochronology data from the central Morocco coastal area document a km-scale exhumation between the Permian and the Early/Middle Jurassic. The related erosion fed sediments to the subsiding Mesozoic basin to the northwest. Basement rocks along the transect were subsequently buried between the Late Jurassic and the Early Cretaceous. From late Early/Late Cretaceous onwards, rocks present along the transect were exhumed to their present-day position.The post-Variscan thermal and geological history of the Anti-Atlas belt in central Morocco is constrained with a transect constructed along strike of the belt (chapter 3). The initial episode occurred in the Late Triassic and led to a km-scale exhumation of crustal rocks by the end of the Middle Jurassic. The following phase was characterised by basement subsidence and occurred during the Late Jurassic and most of the Early Cretaceous. The basement rocks were then slowly brought to the surface after experiencing a km-scale exhumation throughout the Late Cretaceous and the Cenozoic. The exhumation episodes extended into the interior of the African tectonic plate, perhaps beyond the sampled belt itself. Exhumation rates and fluxes of material eroded from the hinterlands of the Moroccan rifted margin were quantified from the Permian (chapter 4). The high denudation rates, obtained in central Morocco during the Early to Middle Jurassic and in northern Morocco during the Neogene, are comparable to values typical of rift flank, domal, or structural uplifts. These are obtained in central Morocco during the Early to Middle Jurassic and in northern Morocco during the Neogene. Exhumation rates for other periods in northern to southern Morocco average around ‘normal’ denudation values. Periods of high production of sediments in the investigated source areas are the Permian, the Jurassic, the Early Cretaceous, and the NeogeneThe Phanerozoic evolution of source-to-sink systems in Morocco and surroundings is illustrated in several maps (chapter 5). Substantial shifts in the source areas were evidenced between the central and northern Moroccan domains during the Middle-Late Jurassic and between the Meseta and the Anti-Atlas during the Early-Late Cretaceous. Finally, the mechanisms responsible for the onset and subsistence of the unpredicted km-scale vertical movements are discussed (chapter 6). We propose that a combination of the large-scale crustal folding, mantle-driven dynamic topography, and thermal subsidence, superimposed to changes in climates, sea level and erodibility of the exposed rocks, were crucial to the timing, amplitude, and style of the observed vertical movements.The km-scale vertical movements will continue to be studied for years to come. Expectantly, this Thesis will deliver sufficiently robust grounds for further elaborated and integrated studies in Morocco and beyond.


Fossil Record ◽  
2020 ◽  
Vol 23 (2) ◽  
pp. 215-236
Author(s):  
Volker Lohrmann ◽  
Qi Zhang ◽  
Peter Michalik ◽  
Jeremy Blaschke ◽  
Patrick Müller ◽  
...  

Abstract. Rhopalosomatidae, currently considered the sister group of the Vespidae, are an enigmatic family of aculeate wasps that originated in the Late Jurassic or Early Cretaceous. Despite their considerable age, very few fossils of the family have been reported – all of them in amber (Miocene Dominican, Miocene Mexican, and mid-Cretaceous Burmese ambers). Here we report a new mid-Cretaceous rhopalosomatid wasp, Cretolixon alatum Lohrmann, gen. et sp. nov., from Burmese (Kachin) amber. This new genus has a unique mixture of characters, some of which are only known from the recent brachypterous genus Olixon and others of which are known only from the recent macropterous genera. Thus, Cretolixon Lohrmann, gen. nov. not only provides further evidence for the monophyly of the family but also contributes evidence for the monophyly of the Rhopalosomatinae. Key characters of the family are discussed, and an updated checklist of the world genera and fossil species and occurrences of Rhopalosomatidae is provided. Additionally, a chemical analysis was performed for three of the newly reported fossils as well as for the amber piece containing the rhopalosomatid larva described by Lohrmann and Engel (2017) to ascertain their amber vs. copal nature and their affinities with each other and previously described Burmese amber.


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