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The earliest pterosaurs

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tions calculated from these extant taxa: estimates were averaged and results (6.92 kg and
6.55 kg) are similar to previously published values. Principal Components Analyses (PCA)
and Discriminant Function Analyses (DFA) of both raw measurements and functional
indices were used to assess locomotor habit. Protypotherium plots closest to fossorial taxa
in the PCA of raw data but plots closest to a generalized mammal (Proechimys) in the PCA
of indices. It is classified as arboreal in the DFA of raw data and as fossorial in the DFA
of functional indices. These results indicate that the limbs of Protypotherium were adapt-
ed for force not speed. The relatively large mass of Protypotherium and the inferred fos-
sorial habits of closely-related notoungulates suggest a fossorial lifestyle is more likely. The
humerus, femur, and manus of Protypotherium most closely resemble the arboreal rodent
Erethizon among extant taxa examined, however. A broader study of modern arboreal and
fossorial taxa would likely help discriminate between the two alternatives.
Thursday 1:30
THE EARLIEST PTEROSAURS
ANDRES, Brian, Yale Dept. of Geology and Geophysics, New Haven, CT
The Triassic record of pterosaurs is limited to five species from central Europe, a species
from Greenland, two wing metacarpals from Gloucester, and about 30 isolated tooth ele-
ments referred to the pterosaurs. The most complete of these isolated elements are two jaw
fragments with in situ teeth from the Dockum Group of Texas. These specimens were found
in sediments of Carnian Age, whereas, the oldest pterosaur specimens are from the Upper
Norian. If these fragments belong to pterosaurs, they would be the oldest known members
of this group and extend its range by about ten million years.
These jaw fragments and the other isolated teeth have been referred to the pterosaur
Eudimorphodon. This taxon is unique among Triassic pterosaurs in having a widespread
distribution, even without considering these teeth. Eudimorphodon is the only Triassic
pterosaur taxon known from more than one described specimen, more than one locality,
found on more than one modern continent, and present in both terrestrial and marine sedi-
ments of most pterosaurs. The teeth of Eudimorphodon are unique among pterosaurs in hav-
ing a multicuspate morphology of up to five large cusps. However, similar dentition is pres-
ent in nonmammaliamorph cynodonts of the same time. The isolated teeth are often identi-
fied as possibly belonging to one or the other. Study of the two more complete jaw frag-
ments from Texas will help infer on whether these isolated teeth belong to pterosaurs and
whether this group is older than previously known.
Analysis of the Texas jaw fragments using Microfocus CTscanning at the University of
Amherst Digital Paleo Lab reveal features that allow the referral of one specimen to the
pterosaur Eudimorphodon, and the other to the Cynodontia. These specimens highlight the
unusual convergence and differences between these two groups. Possible reasons for this
level of convergence are explored. Phylogenetic analyses by this and other authors do not
recover Eudimorphodon as basal pterosaur taxon. This would imply an unrecorded radia-
tion of pterosaurs in the Carnian or even earlier. A review of the referred isolated teeth
reveals that most are cynodonts or other archosauriforms. Some teeth are similar to but lie
outside the diversity of the Texas and other Eudimorphodon specimens.
Poster Session III
MAMMALS AND MARKER BEDS IN THE WASATCH AND GREEN RIVER FOR-
MATIONS: EOCENE BIOSTRATIGRAPHY NEAR FREIGHTER GAP, GREAT
DIVIDE BASIN, SOUTHWESTERN WYOMING
ANEMONE, Robert, Western Michigan Univ., Kalamazoo, MI; WATKINS, Ron, Curtin
Univ. of Technology, Perth, Australia; MOORE, Bill, Southern Illinois Univ., Carbondale,
IL; STROIK, Laura, Arizona State Univ., Tempe, AZ
Recent paleontological investigations in Paleocene and Eocene terrestrial deposits of the
Great Divide Basin have greatly increased our knowledge of the evolution of early Tertiary
mammals in a previously little-studied sedimentary basin along the continental divide in
SW Wyoming. During the past ten summer field seasons we have collected and catalogued
7000 fossil mammals from nearly 80 localities in Clarkforkian and Wasatchian deposits
across the Paleocene-Eocene boundary. These fossils have come from a number of differ-
ent areas within this large (ca. 10,000 square kilometers) basin, including the vicinity of
Steamboat Mountain and Freighter Gap in the northern part of the basin. In this paper we
report new results concerning the presence of geological marker beds and their stratigraph-
ic relationships to fossil mammal localities in the Steamboat Mountain-Freighter Gap
region of the Great Divide Basin. The early Tertiary deposits of the Wasatch formation in
this region are of fluvial origin, and comprise more than 3000 feet of essentially flat lying
sandstones, siltstones, oil and clay shales, and coal beds.The first marker unit is a sandstone
bed with bivalves and gastropods that closely resembles a unit figured by Pipiringos in
1961, and which he considered to be in the lower part of the Luman tongue of the Green
River Formation. It occurs near the 7100 ft contour in T24N, R100W, approximately 5 miles
east of Freighter Gap. The second marker bed comprises a sequence of stromatolites, oil
paper shales, ostracod-bearing sandstone, and a gastropod and bivalve-bearing limestone. It
is found less than a mile to the north of the first marker, at the 7500 foot contour, where it
caps the fossiliferous sequence in this part of the Great Divide Basin. The fossil mammals
recovered from approximately 20 different localities in the Freighter Gap area (ca. 2500
specimens) are clearly of Wasatchian age, and can be tied into a local stratigraphic column
in relation to these marker beds and the general stratigraphy of the region.
Saturday 12:00
WERE END-PERMIAN TERRESTRIAL VERTEBRATE COMMUNITIES
UNUSALLY SUSCEPTIBLE TO EXTINCTION?
ANGIELCZYK, Kenneth, Univ. of Bristol, Bristol, United Kingdom; ROOPNARINE,
Peter, California Academy of Sciences, San Francisco, CA; WANG, Steve, Swarthmore
College, Swarthmore, PA
The end-Permian mass extinction was the largest extinction event of the Phanerozoic, with
strong effects on marine and terrestrial communities, but its causes remain obscure. Part of
this uncertainty stems from the fact that few unique mechanisms have been definitively
associated with mass extinctions. Regardless of their ultimate causes, however, it is clear
that mass extinctions represented times of severe ecological crisis, during which ecological
community functions were altered or shifted into new states. Thus, many of the species that
became extinct during intervals of mass extinction probably did not succumb to the direct
effects of abiotic triggers, but instead were victims of the resultant ecological crises and fail-
ing communities. In particular, the trophic relationships that exist between different organ-
isms in a community may make them vulnerable to cascades of secondary effects, in which
the effects of a perturbation of some members of a community can spread throughout a food
web, potentially causing its collapse. However, this raises the question of whether commu-
nities of differening trophic connections are equally susceptible to extinction.
To address this question, we constructed probabilistic models of trophic networks for
eight terrestrial vertebrate communities, ranging in age from late Middle Permian to early
Middle Triassic, from the Karoo Basin of South Africa, and subjected them to different
types of perturbations. Our results indicate that the communities’ extinction resistances are
not uniform. For example, the earliest Triassic Lystrosaurus Assemblage Zone community
is more resistant to a bottom-up trophic perturbation than any of the other communities.
However, the latest Permian Dicynodon Assemblage Zone community is only marginally
more vulnerable, indicating that a large disturbance would be necessary to account for
observed levels of extinction. These results are significant because they help to focus our
search for potential causes of the end-Permian extinction, and can provide insight into
whether mass extinctions have acted over time to increase the extinction-resistance of com-
munities.
Student Poster Session
SYSTEMATICS OFTHE CHALICOTHERIINAE (PERISSODACTYLA) AND THE
IMPORTANCE OF REVISING OLD COLLECTIONS
ANQUETIN, Jérémy, The Natural History Museum, London, United Kingdom
Chalicotheres are quite peculiar perissodactyls with large bifid claws instead of hooves and
reduced hindlimbs. Members of the subfamily Chalicotheriinae present the most derived
morphology among chalicotheres, with extremely reduced hindlimbs, quite elongate fore-
limbs and a knuckle-walking gait (all converging toward a gorilla-like posture). Miocene
chalicotheriines from France and Germany were also the first chalicotheres to be described
at the beginning of the 1800s. During the main part of the 1900s, it was assumed that there
was only one chalicotheriine genus throughout the Miocene: Chalicotherium. Recently, a
new taxon from Greece (Anisodon macedonicus) shed new light on chalicotheriine phyloge-
ny and it was proposed that middle and late Miocene taxa should be divided into two gen-
era.
In order to test this hypothesis, I revised historic specimens of Anisodon grande from
France (including the first known chalicothere skull). Some of these remains have not been
studied since 1890 and most have never been accurately described. In addition, new remains
of Chalicotherium goldfussi from Saint-Gaudens, France are described, including the first
known complete mandibular symphysis which indicates that C. goldfussi has three incisors.
Based on these new data, a cladistic analysis was performed and its results are reported here.
The division of middle and late Miocene taxa into two main clades (Anisodon and
Chalicotherium) is strongly supported. Furthermore, this analysis proposes a novel pattern
of relationships. Nestoritherium sivalense, C. wuduensisand ‘C. goldfussi’from Titov Veles
(Macedonia) are no longer close relatives of C. goldfussi as previously thought, but rather
belong to the genus Anisodon and become A. sivalense, A. wuduensis and A. sp., respective-
ly. Recently described Kalimantsia needs to be reviewed to properly assess its relationships
and nomenclature.
Poster Session I
THE FIRST DINOSAUR REMAINS FROM THE SUSTUT BASIN, NORTH-CEN-
TRAL BRITISH COLUMBIA, CANADA
ARBOUR, Victoria, Dalhousie Univ., Dartmouth, NS, Canada; GRAVES, Milton,
Dalhousie Univ., Halifax, NS, Canada
Dinosaur bones discovered in 1971 represent the first dinosaur fossils reported from the
Sustut Basin, and also the first dinosaur skeletal material discovered in British Columbia.
The bones were discovered in a talus slope during thorium and uranium exploration near the
intersection of Birdflat Creek and Sustut River (NTS map sheet 94D, McConnell Creek
Area). Outcropping in the area are Late Cretaceous rocks of the Sustut Group, representing
fluvial and lacustrine deposition in an intermontane successor basin. Information from the
original field notes, as well as examination of the siltstone matrix surrounding the bones,
suggests that the bones may have originated from the Brothers Peak Formation (Campanian
to Maastrichtian). Elements recovered include the distal fragment of a tibia and fibula,
seven pedal phalanges including two unguals, the proximal fragment of a humerus, a com-
plete radius, a poorly preserved ulna, and a possible fragment of the pelvic girdle. Although
JVP 26(3) September 2006—ABSTRACTS 37A
... A relatively high number of skeletal remains from Italy, Austria, Greenland and USA, as well as many isolated teeth from Europe and North America, have subsequently been referred to this genus, based mainly on the presence of two to four accessory cusps in the tooth crowns (Dalla Vecchia, 2013). These specimens were initially referred to E. ranzii (MPUM 6009;Wild, 1979;MCSNB 8950;Wild, 1994;and BSP 1994 I 51;Wellnhofer, 2003), to a new Eudimorphodon species (MFSN 1797, holotype of E. rosenfeldi (see Dalla Vecchia, 1995 and MGUH VP 3393, holotype of E. cromptonellus (see Jenkins et al., 2001)), or just to the genus Eudimorphodon (Clemens, 1980;Hahn, Lepage & Wouters, 1984;Chatterjee, 1986;Murry, 1986;Cuny, 1995;Cuny, Godefroit & Martin, 1995;Godefroit, 1997;Godefroit & Cuny, 1997;Godefroit et al., 1998, 2004a, 2004b, 2006Andres, 2006;Andres & Myers, 2013). However, most of the isolated teeth are probably referable to cynodont therapsids (Andres, 2006;Dalla Vecchia, 2013). ...
... A relatively high number of skeletal remains from Italy, Austria, Greenland and USA, as well as many isolated teeth from Europe and North America, have subsequently been referred to this genus, based mainly on the presence of two to four accessory cusps in the tooth crowns (Dalla Vecchia, 2013). These specimens were initially referred to E. ranzii (MPUM 6009;Wild, 1979;MCSNB 8950;Wild, 1994;and BSP 1994 I 51;Wellnhofer, 2003), to a new Eudimorphodon species (MFSN 1797, holotype of E. rosenfeldi (see Dalla Vecchia, 1995 and MGUH VP 3393, holotype of E. cromptonellus (see Jenkins et al., 2001)), or just to the genus Eudimorphodon (Clemens, 1980;Hahn, Lepage & Wouters, 1984;Chatterjee, 1986;Murry, 1986;Cuny, 1995;Cuny, Godefroit & Martin, 1995;Godefroit, 1997;Godefroit & Cuny, 1997;Godefroit et al., 1998, 2004a, 2004b, 2006Andres, 2006;Andres & Myers, 2013). However, most of the isolated teeth are probably referable to cynodont therapsids (Andres, 2006;Dalla Vecchia, 2013). ...
... These specimens were initially referred to E. ranzii (MPUM 6009;Wild, 1979;MCSNB 8950;Wild, 1994;and BSP 1994 I 51;Wellnhofer, 2003), to a new Eudimorphodon species (MFSN 1797, holotype of E. rosenfeldi (see Dalla Vecchia, 1995 and MGUH VP 3393, holotype of E. cromptonellus (see Jenkins et al., 2001)), or just to the genus Eudimorphodon (Clemens, 1980;Hahn, Lepage & Wouters, 1984;Chatterjee, 1986;Murry, 1986;Cuny, 1995;Cuny, Godefroit & Martin, 1995;Godefroit, 1997;Godefroit & Cuny, 1997;Godefroit et al., 1998, 2004a, 2004b, 2006Andres, 2006;Andres & Myers, 2013). However, most of the isolated teeth are probably referable to cynodont therapsids (Andres, 2006;Dalla Vecchia, 2013). Isolated multicusped teeth from Triassic rocks cannot be unequivocally referred to pterosaurs because of the convergent morphology of the teeth of some pterosaurs, cynodonts and also tanystropheid archosauromorphs. ...
Seazzadactylus venieri gen. et sp. nov., a new pterosaur (Diapsida: Pterosauria) from the Upper Triassic (Norian) of northeastern Italy
Article
Full-text available
  • Jul 2019
A new non-monofenestratan pterosaur with multicusped dentition, Seazzadactylus venieri, is described from the Upper Triassic (middle-upper Norian) of the Carnian Prealps (northeastern Italy). The holotype of S. venieri preserves a complete mandibular and maxillary dentition, along with a nearly complete premaxillary one, showing unique features. Furthermore, the arrangement of the premaxillary teeth and the shape of jugal, pterygoid, ectopterygoid, scapula and pteroid are unique within non-monofenestratan pterosaurs. S. venieri is similar and closely related to Carniadactylus rosenfeldi and Austriadraco dallavecchiai, which are also from the Alpine middle-upper Norian of Italy and Austria, respectively. In a parsimony-based phylogenetic analysis, S. venieri is found to nest within a clade of Triassic pterosaurs composed of Arcticodactylus cromptonellus, Austriadraco dallavecchiai, Carniadactylus rosenfeldi and a trichotomy of Raeticodactylus filisurensis, Caviramus schesaplanensis and MCSNB 8950. This unnamed clade is basal within the Pterosauria, but is not the basalmost clade. Eudimorphodon ranzii lies outside this clade and is more derived, making the Eudimorphodontidae paraphyletic. S. venieri increases the diversity of Triassic pterosaurs and brings the number of pterosaur genera and species in the Dolomia di Forni Formation to four.
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... Although the Triassic pterosaur record has increased notably since the first scientific description of a Triassic pterosaur specimen over 35 years ago (Zambelli 1973), pterosaur material from this period is still relatively rare. The oldest occurrence of pterosaurs in Texas, and likely the oldest occurrence worldwide (Barrett et al. 2008), is a partial mandible from the Kalgary Quarry in the Tecovas Formation of the Dockum Group that has been identified as Eudimorphodon sp. that has been dated to the Upper Carnian (Murry 1986(Murry , 1989Lucas & Luo 1993;Andres 2006) but is at least as old as the early Norian (Olsen et al. 2011). Aside from this specimen, unequivocal occurrences of Triassic pterosaurs are known only from Austria, England, Greenland and Italy (Barrett et al. 2008). ...
... It shares the synapomorphy of tall cusps on its teeth (character 121: state 4) with the other Eudimorphodon species recovered as a monophyletic group in the phylogenetic analysis. The taxonomic affinities of numerous isolated multicusped teeth also recovered from the Kalgary Quarry (Murry 1986) have yet to be determined but are currently not considered referable to the Pterosauria (Andres 2006). Chatterjee (1986) reported both cranial and postcranial material of a Eudimorphodon-like pterosaur from the Post Quarry in the Lower Norian Cooper Canyon Formation of the Dockum Group. ...
... Another Upper Triassic specimen, a partial maxilla found in the Kalgary Quarry, was initially attributed to Eudimorphodon along with the mandibular material from the same locality (Murry 1986(Murry , 1989Lucas & Luo 1993). However, subsequent re-evaluation of this specimen determined that it was referable to the Cynodontia rather than Pterosauria (Andres 2006). The Kalgary specimens are part of an ongoing project and will only be discussed relative to published accounts. ...
Lone Star Pterosaurs
Article
Full-text available
  • Sep 2012
  • EARTH ENV SCI T R SO
The state of Texas has one of the greatest records of pterosaurs in the world, surpassing all other US states and most countries in the number of occurrences. Uniquely, this record extends over the entire 150+ million history of the Pterosauria. A review of this pterosaur record confirms at least 30 pterosaurs known from 13 occurrences, including five valid species. The holotypes of two of these species have been described before and are diagnosed and erected here as the new species Radiodactylus langstoni, gen. et sp. nov., named in honour of Dr. Wann Langston Jr, the father of Texas pterosaurology, and Alamodactylus byrdi, gen. et sp. nov.. Phylogenetic analysis of all Texas pterosaurs that can be coded for more than one character confirms that these species are distinct from others and occupy phylogenetic positions close to their original classifications. Radiodactylus langstoni is recovered as a non-azhdarchid azhdarchoid, Quetzalcoatlus northropi as an azhdarchid, Alamodactylus byrdi as a non-pteranodontoid pteranodontian, Aetodactylus as a pteranodontoid, and Coloborhynchus wadleighi as an ornithocheirid. The presence of eudimorphodontid, dsungaripterid, as well as other azhdarchid and pteranodontoid pterosaurs, is also confirmed in Texas.
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... from the uppermost Triassic bonebeds of Europe and North America) are difficult to distinguish from those of Triassic pterosaurs (see Clemens 1980;Hahn et al. 1984;Sigogneau-Russell & Hahn 1994). Andres (2006) considers isolated teeth referred in the literature to Eudimorphodon as belonging to cynodonts or other archosauriforms. A few teeth from the Hallau 'Rhaetian' bonebed (Switzerland) that Peyer (1956) referred to synapsids were noted to have striking resemblances to cheek teeth of Eudimorphodon ranzii Zambelli 1973 (Fig. 2e) and Peteinosaurus zambellii Wild 1979 (Fig. 2f ) by Wild (pers. ...
... 9.5). Heckert (2004, Andres (2006), one of the two specimens belongs to Eudimorphodon and the other belongs to a cynodont, but that affirmation has not yet been explained in detail. According to Lucas & Luo (1993, p. 310), the vertebrates from the close NMMNH 1430 locality (upper Kalgary locality in Heckert 2004), also in the Tecovas Formation (Heckert 2004), include 'a Eudimorphodon-like pterosaur', but no further information was given by those authors. ...
Triassic pterosaurs
Article
  • Aug 2013
Pterosaurs are a clade of highly specialized, volant archosauromorphs recorded from the Upper Triassic to the uppermost Cretaceous. Problematic remains referred to the Pterosauria are reported from the Triassic of Europe and both North and South America, but unequivocal pterosaur specimens are only known from the Alps (Italy, Austria and Switzerland: Preondactylus buffarinii, Austriadactylus cristatus, Peteinosaurus zambellii, Eudimorphodon ranzii, Carniadactylus rosenfeldi, Caviramus schesaplanensis and Raeticodactylus filisurensis) and Greenland (‘Eudimorphodon’ cromptonellus). Pterosaurs are diagnosed mostly by features associated with the advent of powered flight. They are generally considered to be archosaurians more closely related to dinosaurs than to crocodilians, but non-archosaurian positions have also been proposed. There is a lack of general agreement about ingroup relationships, particularly among the basal pterosaurs. Triassic pterosaurs differ from other non-pterodactyloid pterosaurs in features of the dentition and caudal vertebral column. A ‘Big Bang’ model for their early history fits better with the fossil record: the earliest unequivocal pterosaurs show a sudden and geographically limited appearance in the fossil record, as well as a relatively high burst of diversity and considerable morphologic disparity. Absence of pterosaur remains from deposits where they are expected to be found suggests that they had not yet evolved in pre-Norian times.
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... Thus, pterosaurs almost certainly had a pre-Carnian origin. The first pterosaurian remains are known from strata of probable late Carnian -early Norian age in North America and include material assigned to Eudimorphodon (Murry 1986;Lucas and Luo 1993;Andres 2006; Figure 3, Table 1). Other pterosaurian remains have been reported from Carnian and Norian sediments in this region, but these specimens are indeterminate (e.g. ...
An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates
Article
Full-text available
  • Dec 2014
The biogeographical history of pterosaurs has received very little treatment. Here, we present the first quantitative analysis of pterosaurian biogeography based on an event-based parsimony method (Treefitter). This approach was applied to a phylogenetic tree comprising the relationships of 108 in-group pterosaurian taxa, spanning the full range of this clade's stratigraphical and geographical extent. The results indicate that there is no support for the impact of vicariance or coherent dispersal on pterosaurian distributions. However, this group does display greatly elevated levels of sympatry. Although sampling biases and taxonomic problems might have artificially elevated the occurrence of sympatry, we argue that our results probably reflect a genuine biogeographical signal. We propose a novel model to explain pterosaurian distributions: pterosaurs underwent a series of ‘sweep-stakes’ dispersal events (across oceanic barriers in most cases), resulting in the founding of sympatric clusters of taxa. Examination of the spatiotemporal distributions of pterosaurian occurrences indicates that their fossil record is extremely patchy. Thus, while there is likely to be genuine information on pterosaurian diversity and biogeographical patterns in the current data-set, caution is required in its interpretation.
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The dawn of the flying reptiles: first Triassic record in the southern hemisphere
Article
Full-text available
  • Mar 2022
Pterosaurs were the first vertebrates to evolve powered flight. The timing of their origin is still debated, and hypotheses range from the end of the Permian Period, to the lower Mesozoic Era, and through to the Middle–Late Triassic epochs. Regardless of when they originated, the oldest records are restricted to the Upper Triassic Norian Stage in the northern hemisphere (Europe, USA and Greenland). We report two new raeticodactylid pterosaurs, Yelaphomte praderioi gen. et sp. nov. and Pachagnathus benitoi gen. et sp. nov. from the upper Norian to Rhaetian Quebrada del Barro Formation in north‐western Argentina. The new specimens (an isolated dentary symphysis, partial rostrum, and distal half of ulna) are the first unequivocal Triassic records of pterosaurs in the southern hemisphere, confirming that the absence of pterosaurs outside north‐western Pangaea during the Late Triassic was the result of poor sampling rather than true absence. These new discoveries provide evidence of a greater diversity of pterosaurs living in terrestrial habitats and a wider global distribution of pterosaurs from the beginning of their evolution on Earth.
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The origin of Pterosaurs
Article
  • Aug 2021
  • EARTH-SCI REV
Our understanding of the pterosaurs' place within the reptilian lineage has had a long and complex history. The unusual morphology of pterosaurs, which is inextricably linked to their habit of powered flight, has generated numerous proposals over the years regarding their exact origin and systematic position. Though it was concluded early on in pterosaur research history that these animals represented a group of derived flying reptiles, their exact origination remained mysterious for a long time and is still somewhat controversial. A rough consensus has now been reached that pterosaurs are derived archosaurs and are likely close relatives of the dinosaurs, united with them in the clade Ornithodira, though some still challenge this view. The anatomical evidence in support of this position close to Dinosauria is also admittedly fairly limited at present, largely owing to a lack of any clear-cut transitional ‘proto-pterosaur’ taxa (albeit that some fragmentary specimens have been suggested to represent exactly this). Differing hypotheses have also recently been put forward as to the exact interrelationships between the pterosaurs and other non-dinosaurian and dinosaurian ornithodirans. Here the previous hypotheses of where pterosaurs fit into the reptilian lineage and the anatomical evidence in support of the current hypotheses are reviewed. Results of new analyses are included that looked to test the origin and systematic position of the Pterosauria using an expanded version of a large anatomical dataset of archosaurs, within which several previously unconsidered early pterosaur taxa and a suit of new anatomical characters were considered. The analyses in this study support the close affinities between pterosaurs and dinosauriforms within Ornithodira; Pterosauria is recovered as the sister-taxon to Lagerpetidae. Such a result suggests that the clade Pterosauria belongs with Lagerpetidae as part of a broader Pterosauromorpha that then, with Dinosauriformes, falls within Ornithodira. The anatomical evidence in support of this position within Ornithodira is also discussed in detail.
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Testing pterosaur ingroup relationships through broader sampling of avemetatarsalian taxa and characters and a range of phylogenetic analysis techniques
Article
Full-text available
  • Jul 2020
The pterosaurs first appear in the fossil record in the middle of the Late Triassic. Their earliest representatives are known from Northern Hemisphere localities but, by the end of the Jurassic Period, this clade of flying reptiles achieved a global distribution, as well as high levels of diversity and disparity. Our understanding of early pterosaur evolution and the fundamental interrelationships within Pterosauria has improved dramatically in recent decades. However, there is still debate about how the various pterosaur subgroups relate to one another and about which taxa comprise these. Many recent phylogenetic analyses, while sampling well from among the known Triassic and Early Jurassic pterosaurs, have not included many non-pterosaurian ornithodirans or other avemetatarsalians. Given the close relationship between these groups of archosaurs, the omission of other ornithodirans and avemetatarsalians has the potential to adversely affect the results of phylogenetic analyses, in terms of character optimisation and ingroup relationships recovered. This study has addressed this issue and tests the relationships between the early diverging pterosaur taxa following the addition of avemetatarsalian taxa and anatomical characters to an existing early pterosaur dataset. This study has, for the first time, included taxa that represent the aphanosaurs, lagerpetids, silesaurids and dinosaurs, in addition to early pterosaurs. Anatomical characters used in other recent studies of archosaurs and early dinosaurs have also been incorporated. By expanding the outgroup taxa and anatomical character coverage in this pterosaur dataset, better resolution between the taxa within certain early pterosaur subclades has been achieved and stronger support for some existing clades has been found; other purported clades of early pterosaurs have not been found in this analysis—for example there is no support for a monophyletic Eopterosauria or Eudimorphodontidae. Further support has been found for a sister-taxon relationship between Peteinosaurus zambelli and Macronychoptera, a clade here named Zambellisauria (clade nov.), as well as for a monophyletic and early diverging Preondactylia. Some analyses also support the existence of a clade that falls as sister-taxon to the zambellisaurs, here named Caviramidae (clade nov.). Furthermore, some support has been found for a monophyletic Austriadraconidae at the base of Pterosauria. Somewhat surprisingly, Lagerpetidae is recovered outside of Ornithodira sensu stricto , meaning that, based upon current definitions at least, pterosaurs fall within Dinosauromorpha in this analysis. However, fundamental ornithodiran interrelationships were not the focus of this study and this particular result should be treated with caution for now. However, these results do further highlight the need for broader taxon and character sampling in phylogenetic analyses, and the effects of outgroup choice on determining ingroup relationships.
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Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years
Article
Full-text available
  • Sep 2018
  • Nat. Ecol. Evol.
Pterosaurs are the oldest known powered flying vertebrates. Originating in the Late Triassic, they thrived to the end of the Cretaceous. Triassic pterosaurs are extraordinarily rare and all but one specimen come from marine deposits in the Alps. A new comparatively large (wing span >150 cm) pterosaur, Caelestiventus hanseni gen. et sp. nov., from Upper Triassic desert deposits of western North America preserves delicate structural and pneumatic details not previously known in early pterosaurs, and allows a reinterpretation of crushed Triassic specimens. It shows that the earliest pterosaurs were geographically widely distributed and ecologically diverse, even living in harsh desert environments. It is the only record of desert-dwelling non-pterodactyloid pterosaurs and predates all known desert pterosaurs by more than 65 Myr. A phylogenetic analysis shows it is closely allied with Dimorphodon macronyx from the Early Jurassic of Britain.
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Pterosaur distribution in time and space: An atlas
Article
  • Dec 2008
Pterosaurs first appeared in the Late Triassic and persisted until the terminal Cretaceous: they achieved a global distribution during the Mesozoic. Here, we attempt to provide the first comprehensive summary of pterosaur distribution through time and space, including information on the taxonomie composition of pterosaur faunas and the lithostratigraphic units in which they occur. We hope that this compilation will be used as a primary research tool, permitting more detailed and rigorous analyses of pterosaur diversity and palaeobiogeography than have been possible to date.
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