Ben Creisler | 3 May 02:05 2016
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[dinosaur] Late Jurassic dinosaur tracksite at Loulle, France


Ben Creisler

A new paper:

Jean-Michel Mazin, Pierre Hantzpergue & Joane Pouech (2016)
The dinosaur tracksite of Loulle (early Kimmeridgian; Jura, France).
Geobios (advance online publication)
doi:10.1016/j.geobios.2016.01.018

More than 1500 sauropod and theropod tracks have been discovered and excavated on the floor of a disused 3800 m2 quarry, near the village of Loulle (French Jura). These levels correspond to a tidal-flat environment, from intertidal to supratidal zone, dated from the earliest Kimmeridgian (~157 M.a.). Eighteen sauropod trackways have been recognized, ranging from 3.8 m to 51.5 m in length. These trackways do not correspond to a unique herd passage, because trackways are diversely oriented, most of them are crossing others and prints are more or less deeply marked, depending of different stages of substratum competence. According to the trackway gauges, the three types (narrow-, medium and wide-gauge) are represented. Some trackways could be referred to the ichnogenus Brontopodus Farlow et al., 1989, and others to Parabrontopodus Lockley et al., 1994a. Based on footprint size, the body-sizes of these 18 sauropod trackways range from tiny (Pes Length < 25 cm) to large individuals (PL > 75 cm), showing a regular continuum of sizes. Several biometrical ratios classically used in sauropod ichnology appear to be closely related to size (e.g., the smallest individuals apparently moved faster than the largest; large individuals are all narrow-gauge while small individuals are all wide-gauge; large specimens are characterized by a high heteropody ratio when the smallest show a low heteropody ratio). Associated with these sauropod trackways, four theropod trackways have also been recorded. Three small to medium-sized theropod are referred to the ichnogenus Carmelopodus Lockley et al., 1998a, while a large individual (PL = 77 cm) is tentatively referred to Megalosauripus Lessertisseur, 1955.

Ben Creisler | 3 May 00:54 2016
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[dinosaur] Lizard hands + raptor beaks + Solenodon's Cretaceous roots + more


Ben Creisler


Some recent non-dino papers that may be of interest:



open access:

Gabriela Fontanarrosa & Virginia Abdala  (2016) 
Bone indicators of grasping hands in lizards. 
PeerJ 4:e1978 



Grasping is one of a few adaptive mechanisms that, in conjunction with clinging, hooking, arm swinging, adhering, and flying, allowed for incursion into the arboreal eco-space. Little research has been done that addresses grasping as an enhanced manual ability in non-mammalian tetrapods, with the exception of studies comparing the anatomy of muscle and tendon structure. Previous studies showed that grasping abilities allow exploitation for narrow branch habitats and that this adaptation has clear osteological consequences. The objective of this work is to ascertain the existence of morphometric descriptors in the hand skeleton of lizards related to grasping functionality. A morphological matrix was constructed using 51 morphometric variables in 278 specimens, from 24 genera and 13 families of Squamata. To reduce the dimensions of the dataset and to organize the original variables into a simpler system, three PCAs (Principal Component Analyses) were performed using the subsets of (1) carpal variables, (2) metacarpal variables, and (3) phalanges variables. The variables that demonstrated the most significant contributions to the construction of the PCA synthetic variables were then used in subsequent analyses. To explore which morphological variables better explain the variations in the functional setting, we ran Generalized Linear Models for the three different sets. This method allows us to model the morphology that enables a particular functional trait. Grasping was considered the only response variable, taking the value of 0 or 1, while the original variables retained by the PCAs were considered predictor variables. Our analyses yielded six variables associated with grasping abilities: two belong to the carpal bones, two belong to the metacarpals and two belong to the phalanges. Grasping in lizards can be performed with hands exhibiting at least two different independently originated combinations of bones. The first is a combination of a highly elongated centrale bone, reduced palmar sesamoid, divergence angles above 90°, and slender metacarpal V and phalanges, such as exhibited by Anolis sp. and Tropidurus sp. The second includes an elongated centrale bone, lack of a palmar sesamoid, divergence angles above 90°, and narrow metacarpal V and phalanges, as exhibited by geckos. Our data suggest that the morphological distinction between graspers and non-graspers is demonstrating the existence of ranges along the morphological continuum within which a new ability is generated. Our results support the hypothesis of the nested origin of grasping abilities within arboreality. Thus, the manifestation of grasping abilities as a response to locomotive selective pressure in the context of narrow-branch eco-spaces could also enable other grasping-dependent biological roles, such as prey handling.


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Jen A. Bright, Jesús Marugán-Lobón, Samuel N. Cobb, and Emily J. Rayfield (2016)
The shapes of bird beaks are highly controlled by nondietary factors.
Proceedings of the National Academy of Sciences (advance online publication)
doi: 10.1073/pnas.1602683113 


Significance

We show that beak and skull shapes in birds of prey (“raptors”) are strongly coupled and largely controlled by size. This relationship means that, rather than being able to respond independently to natural selection, beak shapes are highly constrained to evolve in a particular way. The main aspects of shape variation seem to correspond with specific genes active during development. Because raptors are not each other’s closest relatives, similar shape constraints may therefore have been present in the ancestors of all modern songbirds, including Darwin’s finches, the classic example of explosive evolution in birds. If this hypothesis is true, then such classic examples may be unusual, needing first to break a genetic lock before their beaks could evolve new shapes.

Abstract

Bird beaks are textbook examples of ecological adaptation to diet, but their shapes are also controlled by genetic and developmental histories. To test the effects of these factors on the avian craniofacial skeleton, we conducted morphometric analyses on raptors, a polyphyletic group at the base of the landbird radiation. Despite common perception, we find that the beak is not an independently targeted module for selection. Instead, the beak and skull are highly integrated structures strongly regulated by size, with axes of shape change linked to the actions of recently identified regulatory genes. Together, size and integration account for almost 80% of the shape variation seen between different species to the exclusion of morphological dietary adaptation. Instead, birds of prey use size as a mechanism to modify their feeding ecology. The extent to which shape variation is confined to a few major axes may provide an advantage in that it facilitates rapid morphological evolution via changes in body size, but may also make raptors especially vulnerable when selection pressures act against these axes. The phylogenetic position of raptors suggests that this constraint is prevalent in all landbirds and that breaking the developmental correspondence between beak and braincase may be the key novelty in classic passerine adaptive radiations.

News:



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Solenodon lineage dates to Cretaceous

Adam L. Brandt, Kirill Grigorev, Yashira M. Afanador-Hernández, Liz A. Paulino, William J. Murphy, Adrell Núñez, Aleksey Komissarov, Jessica R. Brandt, Pavel Dobrynin, J. David Hernández-Martich, Roberto María, Stephen J. O’Brien, Luis E. Rodríguez, Juan C. Martínez-Cruzado, Taras K. Oleksyk & Alfred L. Roca (2016)
Mitogenomic sequences support a north–south subspecies subdivision within Solenodon paradoxus.
Mitochondrial DNA Part A (advance online publication)
DOI:10.3109/24701394.2016.1167891

Solenodons are insectivores found only in Hispaniola and Cuba, with a Mesozoic divergence date versus extant mainland mammals. Solenodons are the oldest lineage of living eutherian mammal for which a mitogenome sequence has not been reported. We determined complete mitogenome sequences for six Hispaniolan solenodons (Solenodon paradoxus) using next-generation sequencing. The solenodon mitogenomes were 16,454–16,457 bp long and carried the expected repertoire of genes. A mitogenomic phylogeny confirmed the basal position of solenodons relative to shrews and moles, with solenodon mitogenomes estimated to have diverged from those of other mammals ca. 78 Mya. Control region sequences of solenodons from the northern (n = 3) and southern (n = 5) Dominican Republic grouped separately in a network, with FST = 0.72 (p = 0.036) between north and south. This regional genetic divergence supports previous morphological and genetic reports recognizing northern (S. p. paradoxus) and southern (S. p. woodi) subspecies in need of separate conservation plans.


News:



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Annie P. McIntosh, Kenshu Shimada and Michael J. Everhart (2016)
Late Cretaceous Marine Vertebrate Fauna from the Fairport Chalk Member of the Carlile Shale in Southern Ellis County, Kansas, U.S.A.
Transactions of the Kansas Academy of Science 119(2):222-230 

The Fairport Chalk (middle Turonian) of the Carlile Shale is an Upper Cretaceous rock unit deposited in the middle of the Western Interior Seaway during the early regressive phase of the Seaway following its peak transgressive phase. The Sternberg Museum of Natural History in Hays, Kansas, U.S.A., houses a collection of marine vertebrate fossils from the Fairport Chalk in southern Ellis County, Kansas. The fossil fauna consists of at least 16 taxa, including 11 chondrichthyans, four osteichthyans, and one reptilian. They show wide ecological diversity, with examples of small to medium-sized opportunistic (Squalicorax), large predaceous (Cardabiodon and Cretoxyrhina), and durophagous (Ptychodus) sharks, as well as small (Enchodus), medium-sized (Plethodidae and Pachyrhizodus), and large (Ichthyodectes) bony fishes. Another notable finding is the occurrence of Telodontaspis agassizensis in which the species was previously known only from Cenomanian deposits, making the specimen from the Fairport Chalk the geologically youngest record for the species.


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William J. May and Joseph D. Hall (2016)
First Occurrence of the Diplocaulid Genus Diploceraspis from the Wellington Formation (Lower Permian) of Northern Oklahoma.
Transactions of the Kansas Academy of Science 119(2): 193–199


Additional field and laboratory investigation of the Midco Member of the middle Wellington Formation, Lower Permian in Noble County, Northern Oklahoma has produced an abundance of vertebrate fossils from a 5 cm thick black silty clay. To date the most notable discovery is bones of the long-horned diplocaulid Diploceraspis which were previously only known from the upper Pennsylvanian and lower Permian of southwest Pennsylvania, southeast Ohio, and northwest West Virginia and the upper Pennsylvanian of southeastern Nebraska. This represents the first reported Permian occurrence of the amphibian Diploceraspis west of the of the Ohio River drainage area of Pennsylvania, Ohio, and West Virginia and therefore greatly increases the geographical range of the genus. Prior to this discovery, Diplocaulus magnicornis was the only long-horned diplocaulid known from the lower Permian of Oklahoma. The identifiable Diploceraspis material recovered consist of 5 partial tabular bones and one dorsal vertebra.

Ben Creisler | 2 May 17:48 2016
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[dinosaur] Ichthyornis from Cenomanian of Central Kansas


Ben Creisler

A new paper:

Tyler R. Shimada  and Laura E. Wilson (2016)
A New Specimen of the Late Cretaceous Bird, cf. Ichthyornis sp., from the Cenomanian of Central Kansas, with Comments on the Size Distribution of Ichthyornis in North America.
Transactions of the Kansas Academy of Science 119(2):231-237 

We describe a previously unreported left humerus of the Late Cretaceous toothed seabird, cf. Ichthyornis sp., from the basal Lincoln Limestone Member (late Cenomanian) of the Greenhorn Limestone Formation in central Kansas. This specimen represents one of the oldest bird specimens in North America, and together with previously described ichthyornithid specimens, it also provides new insights into the size distribution of the fossil taxon. Our analysis indicates that Ichthyornis body size remained relatively consistent throughout its temporal range from the Cenomanian through the Campanian. The present fossil record suggests that Ichthyornis measured up to about 0.5 m in skeletal wingspan, 0.2 m in height, and 0.3 m in skeletal length.
Ben Creisler | 2 May 17:32 2016
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[dinosaur] Siberian dinosaur graveyard + feathered dinosaurs in art + more


Ben Creisler


Some recent items:


Siberian dinosaur graveyard may hold clues to climate change


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Dinosaur tracks



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Triassc Isochirotherium track found near Olesa de Montserrat is best preserved in Spain (in Spanish)


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Sauropocalypse in Utah





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Titanosaur leg bone to go on display in Brazil (in Portuguese)


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Dinosaur exhibit at museum in Baixada Santista in Brazil (with video) (in Portuguese)




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Fish-eating enantiornithine from China (in Chinese)


Alessandro Marisa | 2 May 17:07 2016
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[dinosaur] R: Titanosaur Tapuiasaurus skull

Dear list-members there're someone that can send me a copy of that paper?

Thank's in advance
Alessandro

--------------------------------------------
Ven 29/4/16, Ben Creisler <bcreisler <at> gmail.com> ha scritto:

 Oggetto: [dinosaur] Titanosaur Tapuiasaurus skull
 A: dinosaur-l <at> usc.edu
 Data: Venerdì 29 Aprile 2016, 23:52

 
 Ben Creislerbcreisler <at> gmail.com

 A new paper (right after Sarmientosaurus skull
 description):
 Jeffrey A. Wilson, Diego Pol, Alberto B.
 Carvalho  and Hussam Zaher (2016)The skull of
 the titanosaur Tapuiasaurus macedoi (Dinosauria: Sauropoda),
 a basal titanosaur from the Lower Cretaceous of
 Brazil.Zoological Journal of the Linnean Society
 (advance online publication)DOI:

10.1111/zoj.12420https://urldefense.proofpoint.com/v2/url?u=http-3A__onlinelibrary.wiley.com_doi_10.1111_zoj.12420_abstract&d=DQIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3-iYtkTr4NSbfPZ-78MeRvL7MKHKd0T6KwjsmuDe3HE&s=D8mMQmzrPjdebzH82RcxHaRFioXTk4HX8Z-WWImPdi4&e= 

 
 Although Titanosauria is the most diverse and
 late-surviving sauropod lineage, cranial elements are known
 for just over 24 of its 70+ genera – the vast majority of
 which are fairly fragmentary and restricted to the Late
 Cretaceous. Only three complete titanosaur skulls have been
 described to date; two of these are from the latest
 Cretaceous (Nemegtosaurus, Rapetosaurus), and the third,
 Tapuiasaurus, is from the Early Cretaceous (Aptian). In this
 contribution, we build on the initial treatment of the taxon
 by providing a complete description of the cranial elements
 that benefits from additional preparation and computed
 tomography imaging. We identify six additional features
 diagnosing Tapuiasaurus macedoi, including a jugal with an
 elongate lacrimal process forming much of the posteroventral
 border of the antorbital fenestra, a lateral temporal
 fenestra divided by a second squamosal–postorbital
 contact, and upper jaw teeth with labial wear facets. We
 directed the new morphological data in Tapuiasaurus as well
 as other observations towards a re-analysis of its
 phylogenetic position within Titanosauria. Our analysis
 yielded 34 most parsimonious trees, most of which recovered
 Tapuiasaurus in a basal position adjacent to the Early
 Cretaceous taxa Malawisaurus and Tangvayosaurus, but two
 trees recovered it within Late Cretaceous nemegtosaurids. We
 explored the effects of missing data and missing
 stratigraphic ranges on our results, concluding that (1)
 when missing data levels are high, resolution of even small
 amounts of that missing data can have dramatic effects on
 topology, (2) taxa that are mostly scored for characters
 that cannot be scored in other taxa may be topologically
 unstable and (3) there were several suboptimal trees that
 had greatly improved stratigraphic fit with relatively
 little compromise in terms of tree
 length.

Ben Creisler | 2 May 05:31 2016
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[dinosaur] Pseudochampsa and Tropidosuchus (Archosauriformes) braincase and neuroanatomy


Ben Creisler


A new paper:



María J. Trotteyn (2016)
Braincase and neuroanatomy of Pseudochampsa ischigualastensis and Tropidosuchus romeri (Archosauriformes, Proterochampsia).
Ameghiniana (advance online publication)
doi:10.5710/AMGH.28.04.2016.2968

Proterochampsids form a clade of archosauriforms endemic to South America, interpreted as the sister-taxon of the crown-group Archosauria. Because of this, aspects of the skull osteology in this group are particularly important to understand the evolutionary radiation of Archosauriformes. The braincase anatomy of archosauriforms was described for several groups, including few proterochampsids. However, paleoneurological studies on basal archosauriforms are scarce, and these were never conducted on proterochampsids, except for few preliminary analyses of Tropidosuchus romeri and Pseudochampsa ischigualastensis. Here we add descriptive information on the braincase and partial endocranial morphology of the type-specimens of the proterochampsids Pseudochampsa ischigualastensis and Tropidosuchus romeri based on CT scans. Reptile Encephalazation Quotient (REQ) and olfactory ratios were calculated for the first the time for a proterochampsid, indicating a high olfactory acuity for Tropidosuchus romeri, and suggesting a lifestyle similar to that of living crocodylians. The neurocranial information presented here is important due the scarcity of such data for Proterochampsidae.

Ben Creisler | 30 Apr 16:40 2016
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[dinosaur] Abdalodon, new cynodont from Upper Permian of South Africa


Ben Creisler


A new paper:

Christian F. Kammerer (2016)
A new taxon of cynodont from the Tropidostoma Assemblage Zone (upper Permian) of South Africa, and the early evolution of Cynodontia.
Papers in Palaeontology (advance online publication)
DOI: 10.1002/spp2.1046

A new taxon of early cynodont, Abdalodon diastematicus gen. et sp. nov., is described. The new taxon is represented by a single skull from the upper Permian Tropidostoma Assemblage Zone (AZ) of the Beaufort Group (Karoo Basin, South Africa), which was previously referred to Procynosuchus delaharpeae. Abdalodon is distinguished from Procynosuchus by the presence of only four upper and three lower incisors, fewer postcanines, a well-developed depression on the lateral surface of the maxilla posterior to the canine root, a tall mandibular symphysis forming a distinct ‘chin’, a relatively short snout, and weak or absent interdigitation of sutures in the interorbital region. These features are shared with the only other Tropidostoma AZ cynodont, Charassognathus gracilis. Abdalodon is distinguished from Charassognathus by its postcanine morphology, the presence of an expanded masseteric fossa, inset postcanine tooth rows, a broader interorbital region, and proportionally shorter temporal region. Most strikingly, Abdalodon has a lengthy diastema between the canines and postcanines on both the maxilla and the dentary. Charassognathus has a short diastema between the upper canine and postcanines, but not the lowers, and diastemata are absent from the tooth rows of Procynosuchus. Phylogenetic analysis recovers Abdalodon as the sister-taxon of Charassognathus, forming a clade (Charassognathidae fam. nov.) at the base of Cynodontia. These taxa represent a previously unrecognized radiation of small-bodied Permian cynodonts. Despite their small size, the holotypes of Abdalodon and Charassognathus probably represent adults and indicate that early evolution of cynodonts may have occurred at small body size, explaining the poor Permian fossil record of the group.
Ben Creisler | 30 Apr 09:21 2016
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[dinosaur] Jack Horner's retirement + Rhamphorhynchus + Missouri's rare dinosaurs + more



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Video of talk about excavating rare dinosaur fossils (hadrosaur bones, tyrannosaurid and dromaeosaur teeth) in Missouri

Monster in the Hollow - The Story of Missouri’s Ozark Dinosaurs by Professor Michael Fix




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Biggest Siberian Psittacosaurus fossil skeleton (80% complete, 2.3 meters long, found in 2014) to go on display in Moscow at the Museum of Paleontology in November;  skull was missing some parts and will be reconstructed on mounted skeleton; real fossil skull will be displayed separately; fossils will later be returned to  Kemerovo Museum in Siberia (in Russian)





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New book "Viaje al Chile prehistórico" (Journey to Prehistoric Chile) features recently discovered dinosaurs (in Spanish)


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How birds survived mass extinction with beaks and seeds




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Zhuchengosaurus maximus skeleton in Zhucheng Dinosaur Museum in China recognized by Guinness Book of Records as largest hadrosaur skeleton on display at 9.1 meters high and 16.6 meters long


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Ben Creisler | 29 Apr 23:59 2016
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[dinosaur] Injured Psittacosaurus from Yixian Formation



Ben Creisler


A new paper:


B. P. Hedrick, C. Gao, A. R. Tumarkin-Deratzian, C. Shen, J. L. Holloway, F. Zhang, K. D. Hankenson, S. Liu, J. Anné and P. Dodson (2016)
An Injured Psittacosaurus (Dinosauria: Ceratopsia) from the Yixian Formation (Liaoning, China): Implications for Psittacosaurus biology.
The Anatomical Record (advance online publication)
DOI: 10.1002/ar.23363


We describe a Psittacosaurus specimen from the Lujiatun beds of the Yixian Formation in Liaoning, China with an abnormality on its left fibula. Although a large number of Psittacosaurus specimens are known, only a single example of a pathologic Psittacosaurus has been previously noted. The specific pathology in the current specimen is believed to be a healed fibular fracture as assessed through a combination of gross morphology, microcomputed tomography (microCT), and histology data. The fracture can be identified using microCT, but the degree of remodeling and the stage of fracture repair are best determined histologically. The fracture callus is made up of radially-oriented spokes of woven bone in a cartilage matrix and the original cortical bone prior to the fracture has been largely eroded. A transverse histologic section taken at the level of the fracture shows the displacement of the proximal and distal parts of the fibula. The Psittacosaurus appears to have survived the break considering the deposition of circumferential non-pathologic bone at the periosteal surface outside of the callus. The combination of gross morphological description, microCT data, and histologic data allowed for a full diagnosis of the abnormality. While some previous authors have preferred gross morphological description above other methods for assessing paleopathologies, it is evident based on this specimen that an amalgam of techniques provides greater clarity to paleopathology diagnoses. Although this Psittacosaurus lived in an environment with many predators, it was able to survive with a fracture on its hindlimb, which undoubtedly would have impacted its locomotion.

Ben Creisler | 29 Apr 23:52 2016
Picon

[dinosaur] Titanosaur Tapuiasaurus skull


Ben Creisler


A new paper (right after Sarmientosaurus skull description):

Jeffrey A. Wilson, Diego Pol, Alberto B. Carvalho  and Hussam Zaher (2016)
The skull of the titanosaur Tapuiasaurus macedoi (Dinosauria: Sauropoda), a basal titanosaur from the Lower Cretaceous of Brazil.
Zoological Journal of the Linnean Society (advance online publication)
DOI: 10.1111/zoj.12420



Although Titanosauria is the most diverse and late-surviving sauropod lineage, cranial elements are known for just over 24 of its 70+ genera – the vast majority of which are fairly fragmentary and restricted to the Late Cretaceous. Only three complete titanosaur skulls have been described to date; two of these are from the latest Cretaceous (Nemegtosaurus, Rapetosaurus), and the third, Tapuiasaurus, is from the Early Cretaceous (Aptian). In this contribution, we build on the initial treatment of the taxon by providing a complete description of the cranial elements that benefits from additional preparation and computed tomography imaging. We identify six additional features diagnosing Tapuiasaurus macedoi, including a jugal with an elongate lacrimal process forming much of the posteroventral border of the antorbital fenestra, a lateral temporal fenestra divided by a second squamosal–postorbital contact, and upper jaw teeth with labial wear facets. We directed the new morphological data in Tapuiasaurus as well as other observations towards a re-analysis of its phylogenetic position within Titanosauria. Our analysis yielded 34 most parsimonious trees, most of which recovered Tapuiasaurus in a basal position adjacent to the Early Cretaceous taxa Malawisaurus and Tangvayosaurus, but two trees recovered it within Late Cretaceous nemegtosaurids. We explored the effects of missing data and missing stratigraphic ranges on our results, concluding that (1) when missing data levels are high, resolution of even small amounts of that missing data can have dramatic effects on topology, (2) taxa that are mostly scored for characters that cannot be scored in other taxa may be topologically unstable and (3) there were several suboptimal trees that had greatly improved stratigraphic fit with relatively little compromise in terms of tree length.
Gregory Paul | 29 Apr 20:53 2016
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Re: [dinosaur] Quaesitosaurus formation

I think I'll list Q as upper Barun Goyot or Nemegt equivalent. That will cover my ass, and I often cite uncertainties in the book when the data is ambiguous. 


-----Original Message-----
From: Joe Smith <uwk <at> sbcglobal.net>
To: Gregory Paul <gsp1954 <at> aol.com>
Sent: Fri, Apr 29, 2016 1:10 pm
Subject: Re: Quaesitosaurus formation

I'd just as soon say Nemegt equivalent, as a more up to date ref used. In fact, even lower (fluvial) Djadokhta is more likely than Barungoyot.
--------------------------------------------
On Fri, 4/29/16, Gregory Paul <gsp1954 <at> aol.com> wrote:

Subject: Re: Quaesitosauris formation
To: uwk <at> sbcglobal.net, dinosaur-l <at> usc.edu
Date: Friday, April 29, 2016, 10:45 AM

I
thought there was something screwy about all this. So what
"formation" do I list Quaest as coming from in a
short entry in a popular book? Nemegt equivalent? (I say
Wealden equivalent for the Bernissart Iguanodon
& Doillodon). 






-----Original Message-----

From: Joe Smith <uwk <at> sbcglobal.net>

To: gsp1954 <gsp1954 <at> aol.com>; tholtz
<tholtz <at> umd.edu>; jaimeheadden
<jaimeheadden <at> gmail.com>; vahedemirjian
<vahedemirjian <at> cox.net>

Sent: Fri, Apr 29, 2016 7:50 am

Subject: Re: Quaesitosauris formation



Some comments:



Maryanska's chapter in the THE AGE OF DINOSAURS IN
RUSSIA AND MONGOLIA is not the most up to date ref on this.
Field research by the now defunct HMNS suggests the
(Quaesitosaurus-bearing) Shar Tsav locality is Nemegt
equivalent (early Maastrchtian). The Barun Goyot formation,
btw, is not necessarily the same age. Although the two units
interfinger at the type locality and elsewhere, some
Barungoyotian strata underlie the Nemegt. And
interfingering, to my knowledge, is only observed in lower
Nemegtian strata.

A "Djadokhtan" age is actually more likely than a
Barungoyotian age (sensu stricto). Sauropods are known from
fluvial strata underlying Tugrik, but have not been found in
Barungoyotian beds. Shar Tsav is most likely lower
Djadokhtan or Nemegt roughly 74-70 Ma.



best,



JS



Gmane