domingo, 10 de janeiro de 2016

[PaleoOrnithology • 2015]

Feitianius paradisi • A New Early Cretaceous Enantiornithine (Aves, Ornithothoraces) from northwestern China with Elaborate Tail Ornamentation

Feitianius paradisi

O’Connor, Li, Lamanna, Wang, Harris, Atterholt & You, 2015

DOI: 10.1080/02724634.2015.1054035

ABSTRACT

We provide a detailed description of a well-preserved enantiornithine specimen (GSGM-05-CM-004) from the Lower Cretaceous (Aptian) Xiagou Formation of northwestern Gansu Province, China, for which we erect the new taxon Feitianius paradisi, gen. et sp. nov. This specimen has a distinctive pelvic morphology and can be further distinguished from all other Mesozoic birds by a unique caudal plumage formed by multiple rectricial morphotypes. This newly documented tail morphology reveals a previously unrecognized level of complexity in the plumage of basal birds. This complex tail-feather morphology has a parallel in extant sexually dimorphic birds in which the males have the most altered tails; thus, we identify this specimen as male. Ornamental tail morphologies, such as the novel tail plumage described here, dominate Enantiornithes. This reinforces hypotheses that sexual selection was a major driving force in the evolution of basal bird plumage.

SYSTEMATIC PALEONTOLOGY

AVES Linnaeus, 1758

ORNITHOTHORACES Chiappe, 1995a

ENANTIORNITHES Walker, 1981
FEITIANIUS PARADISI, gen. et sp. nov.

Holotype — GSGM-05-CM-004, an incomplete but articulated specimen preserving the caudal half of the skeleton (mostly inleft lateral view) on a single slab, including carbonized vestigesof the caudal body coverts, rectrices, and keratinous pedalungual sheaths.

Etymology — Feitianius paradisi, meaning Paradise’s feitian (飞天), referring to the hundreds of paintings of feitian, or ‘flying apsara,’ in the Mogao caves that are not far from the type locality. Like the new species, the feitian were beautiful flying creatures. ‘Paradisi’ (Latin, genitive ‘from paradise’) refers to the similarity in tail morphology between the new fossil and the highly sexually dimorphic plumages of extant birds of paradise. For fun, we decided to masculinize the genus name because the holotype specimen appears to be a male.

Locality and Horizon — Lower Cretaceous (lower–middle Aptian) (124–120 Ma; (Suarez et al., 2013) Xiagou Formation,near Changma Village, Yumen City, Gansu Province, northwestern China.

Taxonomic Remarks — The specimen can be referred to Enantiornithes based on its possession of the following characters: excavated thoracic vertebrae with centrally located parapophyses; distinctive, large pygostyle with craniodorsal fork, ventrolateral processes, and distal constriction; ischium with strap-like proximodorsal process; and reduced metatarsal IV. Specimen GSGM-05-CM-004 can be differentiated from Qiliania graffini Ji et al., 2011, another enantiornithine from the same formation, by several features. First, Feitianius paradisi bears a medial plantar crest on metatarsal II (absent in Q. graffini).Although the proportions of the pubis and ischium are similar between the two taxa, the dorsal (caudal) margin of the pubis and ventral (cranial) margin of the ischium are concave in F. paradisi, whereas both of these surfaces are relatively straight in Q. graffini. Furthermore, the proportions of the pedal digits are quite different: the combined length of digit III compared with that of metatarsal III is 1.05 in the new species compared with0.92 in Q. graffini; the same ratio for digit II is 0.77 in F. paradisi and 0.70 in Q. graffini. In addition, in F. paradisi, the hallucal claw is comparatively more recurved and the penultimate phalanx of digit III is subequal in length to the proximal phalanx (the proximal phalanx is longest in Q. graffini).

The pubis of the indeterminate Xiagou Formation enantiornithine GSGM-04-CM-007 is rod-like, and its distal end is curved 90 to the proximal shaft (Lamanna et al., 2006), whereas in Feitianius the pubis is dorsoventrally compressed and ends in a pubic boot. Unfortunately, there are no overlapping skeletal elements to comparewith Dunhuangia lii Wang et al., 2015, a newly described enantiornithine from Changma (Wang et al., 2015). Compared with other enantiornithines, the pygostyle is proportionally shorterthan in species of the Longipterygidae, the tarsometatarsus is considerably more gracile than in all species within the Bohaiornithidae or Avisauridae, and the metatarsal and digit I are shorter than in species of the Pengornithidae. Feitianius paradisiis most similar to Jehol ‘cathayornithiforms’ such as species of Cathayornis, Eoenantiornis, Protopteryx, and Sinornisbut differs from these taxa in the detailed anatomy of the pelvic girdle.

Jingmai K. O’Connor, Da-Qing Li, Matthew C. Lamanna, Min Wang, Jerald D. Harris, Jessie Atterholt and Hai-Lu You. 2015. A New Early Cretaceous Enantiornithine (Aves, Ornithothoraces) from northwestern China with Elaborate Tail Ornamentation. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1054035

ResearchGate.net/publication/288887552_A_new_Early_Cretaceous_enantiornithine_Aves_Ornithothoraces_from_northwestern_China_with_elaborate_tail_ornamentation

Feitianius, new enantiornithine from Early Cretaceous of China

https://twitter.com/pantheo27705718/status/682492589375766528

[PaleoOrnithology • 2016]

Cratoavis cearensis • A New Genus and Species of Enantiornithine Bird from the Early Cretaceous of Brazil

ABSTRACT

The fossil record of birds in Gondwana is almost restricted to the Late Cretaceous. Herein we describe a new fossil from the Araripe Basin, Cratoavis cearensis nov. gen et sp., composed of an articulated skeleton with feathers attached to the wings and surrounding the body. The present discovery Considerably extends the record time of the enantiornithes birds at South America to the Early Cretaceous. For the first team, an almost complete and articulated skeleton of an Early Cretaceous bird from South America is documented.

Keywords: Cratoavis cearensis nov. gen et sp .; Araripe Basin; fossil bird

SYSTEMATIC PALEONTOLOGY

Aves Linnaeus 1758

Ornithothoraces Chiappe 1996

Enantiornithes Walker 1981

Euenantiornithes Chiappe & Walker 2001

http://novataxa.blogspot.com/2015/06/enantiornithes-gondwana-feathers.html

Cratoavis cearensis nov. gen. et sp. (Figs. 3 and 4)

Etymology: Cratoavis nov. gen., the generic name derives from the combination of the Crato Member lithostratigraphic unit, where the specimen was found, and the zoological group Aves. The specific epithet cearensis refers to the Ceará State, where the fossil was collected.

Locality and horizon: Pedra Branca Mine, Nova Olinda County, Ceará State, Brazil (7° 6´51.9´´ S and 39° 41´46.9´´ W). Araripe Basin, Santana Formation, Crato Member (Early Cretaceous, Aptian).

This formation has yielded abundant and exceptionally preserved fossils of a large variety of plants and animals, representing one of the best well-known terrestrial ecosystems for the Early Cretaceous. Isolated feathers probably belonging to birds have been described from these beds, as well as succinct reports on avian skeletons associated with poorly preserved feathers.

Cratoavis cearensis & Mirischia asymmetrica

Illustration: Deverson Pepi || commons.wikimedia.org

CONCLUSIONS

Cratoavis cearensis nov. gen. et sp. constitutes the first named bird from the Mesozoic of Brazil and the Early Cretaceous of South America. It constitutes an important addition to the meager record of South American Cretaceous birds, and constitutes one of the more complete Mesozoic bird specimen from Gondwana. It also expands the list in which skeletal elements have been found in association with feathers, including long tail rectrices.

Ismar Carvalho, Fernando E. Novas, Federico L. Agnolin, Marcelo P. Isasi, Francisco I. Freitas and Jose A. Andrade. 2015. A New Genus and Species of Enantiornithine Bird from the Early Cretaceous of Brazil. Brazilian Journal of Geology. 45(2): 161-171. DOI: 10.1590/23174889201500020001

http://www.scielo.br/pdf/bjgeo/v45n2/2317-4889-bjgeo-45-02-00161.pdf

http://www.igeo.ufrj.br/~ismar/2/2_62.pdf

RESUMO: No Gondwana, o registro fóssil de aves está praticamente restrito ao Cretáceo Superior. Neste estudo é descrito um novo fóssil da Bacia do Araripe, Cratoavis cearensis nov. gen. et sp., composto por um esqueleto articulado com penas conectadas às asas e circundando o corpo. A presente descoberta amplia consideravelmente o intervalo temporal de registro das aves Enantiornithes na América do Sul ao Cretáceo Inferior. Pela primeira vez, um esqueleto articulado e quase completo de uma ave do Cretáceo Inferior da América do Sul é documentado.

PALAVRAS-CHAVE: Cratoavis cearensis nov. gen. et sp.; Bacia do Araripe; Ave fóssil.

Ismar de Souza Carvalho, Fernando E. Novas, Federico L. Agnolín, Marcelo P. Isasi, Francisco I. Freitas and José A. Andrade. 2015. A Mesozoic Bird from Gondwana preserving Feathers. Nature Communications. DOI: 10.1038/ncomms8141

Photos: Dinosaur-Era Bird Sported Ribbonlike Feathers

http://www.livescience.com/51035-photos-bird-ribbonlike-feathers.html

[PaleoOrnithology • 2016]

Is the “Genyornis” Egg of A Mihirung or Another Extinct Bird from the Australian Dreamtime?

Fig. 1. A, Comparison of SAM P.42421, the ‘Spooner Egg’, left, attributed to Genyornis newtoni, and an emu egg (Dromaius novaehollandiae) SAM B.9899. B, Comparison of femora of Genyornis newtoni SAM P13864 and a 22 cm long Dromaius novaehollandiae femur (FUR 058). C, The Spooner Egg as partly excavated revealing its intact nature; photograph by Gifford Miller, INSTAAR, Colorado. D, The Spooner Egg in situ as found by NS on 23rd July 2000, photograph by Gifford Miller using a reflex camera, and is the best image taken of the egg prior to excavation.

Scale bars in A and B = 10 cm. DOI: 10.1016/j.quascirev.2015.12.011

Highlights

• Eggshell previously identified as from Genyornis newtoni is reassessed.

• Egg size and microstructure is not conducive with an identity as an dromornithid.

• We suggest that this eggshell is from one of the extinct megapodes in Progura.

• Previous assessments of the timing of Genyornis extinction relate to Progura species.

Abstract

The iconic Australian Genyornis newtoni (Dromornithidae, Aves) is the sole Pleistocene member of an avian clade now hypothesized to be alternatively in Anseriformes or the sister group of crown Galloanseres. A distinctive type of fossil eggshell commonly found in eroding sand dunes, has been referred to Genyornis newtoni since the 1980s. The 126 by 97 mm Spooner Egg, dated at 54.7 ± 3.1 ka by optical dating of its enclosing sediments, is a complete specimen of this eggshell type that was reconstructed from fragments of a broken egg. We show that the size of the eggs from which this ‘Genyornis’ eggshell derives, either as predicted from measurements of fragments, or as indicated by the Spooner Egg, is unexpectedly small given the size of G. newtoni, which has an estimated mass of 275 kg, or about seven times the mass of the emu that has a similar sized egg. We compared the microstructure of the putative Genyornis eggshell to that of other dromornithids and a range of galloanseriform taxa using several microcharacterisation techniques. The ‘Genyornis’ eggshell displays a mosaic of oological characters that do not unambiguously support referral to any known modern bird. Its shell structure, coupled with chemical compounds in the accessory layer, makes it unlikely to have been laid by a dromornithid, whereas several characters support a megapode origin. A potential candidate for the bird that laid the putative ‘Genyornis’ eggs in the Pleistocene fossil avifaunal record has been ignored: Progura, a genus of extinct giant megapodes, whose species were widespread in Australia. Regression of egg size of megapodes and body mass shows that the Spooner Egg approximates the expected size for eggs laid by species of Progura. We advance the suggestion that the fossil eggshell hitherto referred to Genyornis newtoni, is more likely to have been laid by species of the giant extinct Progura. As megapodes, the species of Progura were obligate ectothermic incubators, which we suggest laid their eggs into a hole dug in sand like the modern megapode Macrocephalon maleo, thus explaining the abundant ‘Genyornis’ eggshell in sand dunes. Referral of this eggshell to Progura means that the fossil record of Genyornis newtoni is limited to bones and the timing of the extinction of this last dromornithid is unknown. In addition, structural similarities of eggshell in megapodes, the putative Genyornis eggshell and dromornithids, raise the possibility that these taxa are phylogenetically more closely related to each other than any is to anseriforms. Specifically, this means that dromornithids might be a sister group to galliforms rather than to or within anseriforms.

Keywords: Eggs; Eggshells; Paleoenvironments; Genyornis newtoni; Dromornithids; Megapodes; Progura; Micro-CT; EBSD; Quaternary; Australia

Conclusions

We have described in detail the structure of putative Genyornis eggshell and raised several obstacles to the hypothesis first advanced by Williams (1981) and accepted thereafter ( Miller et al., 1999 and Miller et al., 2005), that this ootype was laid by the giant dromornithid G. newtoni. Rather, we think it more likely that it was laid by one of the several species of giant megapodes in the genus Progura that were widespread in the Pleistocene in Australia.

Gerald Grellet-Tinner, Nigel A. Spooner and Trevor H. Worthy. 2016. Is the “Genyornis” Egg of A Mihirung or Another Extinct Bird from the Australian Dreamtime? QUATERNARY SCIENCE REVIEWS. 133:147-164 DOI: 10.1016/j.quascirev.2015.12.011

ResearchGate.net/publication/289500812_Is_the_Genyornis_egg_of_a_mihirung_or_another_extinct_bird_from_the_Australian_dreamtime

[Paleontology • 2016]

Makhaira rossica • Peculiar Macrophagous Adaptations in A New Cretaceous Pliosaurid

Makhaira rossica

Fischer, Arkhangelsky, Stenshin, Uspensky, Zverkov & Benson, 2015

DOI: 10.1098/rsos.150552

Abstract

During the Middle and Late Jurassic, pliosaurid plesiosaurs evolved gigantic body size and a series of craniodental adaptations that have been linked to the occupation of an apex predator niche. Cretaceous pliosaurids (i.e. Brachaucheninae) depart from this morphology, being slightly smaller and lacking the macrophagous adaptations seen in earlier forms. However, the fossil record of Early Cretaceous pliosaurids is poor, concealing the evolution and ecological diversity of the group. Here, we report a new pliosaurid from the Late Hauterivian (Early Cretaceous) of Russia. Phylogenetic analyses using reduced consensus methods recover it as the basalmost brachauchenine. This pliosaurid is smaller than other derived pliosaurids, has tooth alveoli clustered in pairs and possesses trihedral teeth with complex serrated carinae. Maximum-likelihood ancestral state reconstruction suggests early brachauchenines retained trihedral teeth from their ancestors, but modified this feature in a unique way, convergent with macrophagous archosaurs or sphenacodontoids. Our findings indicate that Early Cretaceous marine reptile teeth with serrated carinae cannot be unequivocally assigned to metriorhynchoid crocodylomorphs. Furthermore, they extend the known diversity of dental adaptations seen in Sauropterygia, the longest lived clade of marine tetrapods.

Systematic description

Plesiosauria Blainville, 1835

Pliosauridae Seeley, 1874

Thalassophonea Benson & Druckenmiller, 2014

Makhaira rossica gen. et sp. nov.

LSIDs: urn:lsid:zoobank.org:pub:2C95C409-72C0-45FE-BF58-608657D5382F (Publication);
urn:lsid:zoob- ank.org:act:F19A595F-D739-4361-9088-84B7B947DC93 (Makhaira);
urn:lsid:zoobank.org:act:258CFACB-27D3-44CF-8B04-A12FDDECA55C (Makhaira rossica)

Figure 2. Rostrum of YKM 68249/1-10.
(a–c) Right premaxilla, in (a) lateral, (b) medial and (c) ventral views. Numbers indicate the position of each alveolus. The ventral premaxilla–maxilla suture is located at the 6th alveolus. Note the procumbent 1st alveolus. (d–e) Anterior part of the symphysis, in (d) anterior, (e) ventral and (f) posterior views.

DOI: 10.1098/rsos.150552

Figure 3. Dentition and mandible of YKM 68249/1-10.
(a) Mandible in dorsal view. (b) Replacement tooth in the 2nd alveolus, showing the trihedral cross section. (c) Base of the 3rd alveolus crown, showing the marked mesiolabial carina (the crown fragment has been glued slightly off its original position). (d) 1st or 2nd post-symphysis replacement tooth, showing distal ridges and serrated carinae. (e,f) Successive zooms of the mesiolabial carinae of a broken off crown lying on the ventral surface of the symphysis (figure 2). (h) Schematic diagram of the carination, drawn from (f). Note the serrated crenulations.

DOI: 10.1098/rsos.150552

Holotype, Horizon and Locality: YKM 68249/1-10, a slightly immature fragmentary skeleton consisting of a partial right premaxilla, the anterior part of the mandible, several teeth, three dorsal vertebrae in anatomical connection, a partial left ischium and a partial right ilium. It is preserved in three dimensions in a series of pyritic limestone nodules found along the banks of the Volga River, 600 m to the north of Slantsevy Rudnik, Ulyanovsk Oblast, Russian Federation (figure 1). The precise level within the section is unknown, but the section only contains Upper Hauterivian (Lower Cretaceous) strata of the Speetoniceras versicolor Zone in this locality.

Etymology: From Latinized Ancient Greek ‘μάχαɩρα’ (mákhaira): a blade with a curved outline and Latin ‘rossica’: Russian.

Figure 4. Postcranial remains of YKM 68249/1-10.
(a–f) Dorsal centrum, in (a) anterior, (b) right lateral, (c) posterior, (d) left lateral, (e) ventral and (f) dorsal views. (g–k) Right ilium in (g) dorsal, (h) medial, (i) lateral, (j) posterior and (k) ventral views. (l–q) Left ischium in (l) anterolateral (glenoid), (m) dorsal, (n) posterolateral, (o) medial, (p) anteromedial and (q) ventral views. (r) Reconstruction of Makhaira rossica based on Late Jurassic pliosaurids and mid-Cretaceos brachauchenines; the orange coloured parts indicate fossils preserved in YKM 68249/1-10.

DOI: 10.1098/rsos.150552

.............................

Discussion and Conclusion

Ecology of Early Cretaceous pliosaurids

Makhaira rossica shares morphological features with both Late Jurassic and Mid-Cretaceous pliosaurids, detailing the tempo of morphological evolution in the early history of Brachaucheninae. Osteological features often associated with macrophagy, and widely present in Middle–Late Jurassic pliosaurids such as the spatulate rostrum and the expanded caniniform teeth were seemingly lost early in the evolution of brachauchenines. However, the incompletely resolved phylogenetic position of Makhaira rossica within Brachaucheninae, and the presence of these features in some other Cretaceous pliosaurid specimens whose phylogenetic affinities were not resolved by our analysis raises a number of questions regarding the evolution and biodiversity of early members of that clade. Specifically, it seems that Early Cretaceous pliosaurids exhibit multiple ecomorphologies that are in need of further study. Because of the poor record of Early Cretaceous pliosaurids, it is still unclear whether trihedral, strongly carinated teeth constitute the ancestral condition of derived thalassophoneans or were acquired convergently in Makhaira rossica, Pliosaurus and currently enigmatic taxa such as ‘Pliosaurus’ rossicus. Parsimony-based methods are ambiguous while likelihood methods suggest that trihedral teeth are a synapomorphy of Pliosaurus + Brachaucheninae, that was subsequently lost within Brachaucheninae. In this scenario, Makhaira rossica thus retained the ancestral state of that trait, but modified it via a unique serration pattern.

Makhaira rossica departs from both Late Jurassic and Cretaceous thalassophoneans by its smaller size: the largest dorsal centrum is 72 mm wide. Nevertheless, fusion of neurocentral suture suggests osteological maturity for this specimen. For comparison, the last cervical centrum of the late Barremian ‘Brachauchenius’ sp. is 117 mm wide, the largest dorsal centrum of Brachauchenius lucasi is 90 mm wide and the width of those of Kronosaurus queenslandicus and ‘Kronosaurus’ boyacensis exceed 150 mm and 170 mm, respectively. Makhaira rossica markedly differs from Cretaceous thalassophoneans by having relatively large teeth and dental adaptations reminiscent of macrophagous predators such as theropod dinosaurs or thalattosuchians crocodyliforms. Unexpectedly, because of their densely serrated and wave-like pattern, the carinae of YKM 68249/1-10 appear larger and more complex than in other macrophagous marine tetrapods such as Mosasaurus hoffmani (V. Fischer 2015, personal observation on ULg PA.25119), Dakosaurus maximus ([54]; V. Fischer 2015, personal observation on ULg PA.6600) or Geosaurus, the latter being regarded as having ‘hypercarnivorous’ adaptations. Makhaira rossica is also unique among plesiosaurs in having trihedral but moderately widely spaced teeth. Contrary to carination and serration, previous authors have not generally assigned a specific functional interpretation to the presence of wide interalveolar spacing. However, we note that the carinated teeth of macrophagous marine reptiles are usually closely spaced.

Makhaira rossica thus indicates that pliosaurids explored previously unrecognized niches during the Early Cretaceous, with the presence of a smaller bodied taxon possessing clear yet distinctive macrophagous adaptations. By being the first sauropterygian to develop complex serration of its carinae, Makhaira rossica further exemplifies the profound diet-driven morphofunctional convergences that evolved among Mesozoic marine reptiles.

Figure 5. Phylogenetic position of Makhaira rossica and ancestral state reconstructions of character 139, related to crown shape. (a) Strict consensus of the maximum-parsimony analysis of the full dataset. (b) Strict consensus of the maximum-parsimony analysis of the reduced dataset. (c) Results of maximum-parsimony method for ancestral state reconstruction (using MESQUITE). (d) Results of likelihood method for ancestral state reconstruction (using CLADDIS).

DOI: 10.1098/rsos.150552

Implications for metriorhynchid extinction

An isolated crown from the Aptian of Sicily (MSNC 4475) has been recently regarded as evidence for the late survival of geosaurine metriorhynchid crocodyliforms, several million years after their supposed extinction [61]. However, although they do not yet co-occur within a single pliosaurid taxon, all the features of MSNC 4475 described in [61] can now be shown to have been present among Cretaceous pliosaurids (‘The conical shape of the tooth crown, noticeable lingual curvature, presence of mesial and distal carinae, and microscopic denticles along the carinae’ [61], p. 610). We also note that MSNC 4475 appears weakly trihedral in apical view ([61]; figure 2f). Moreover, fine, smooth and widely spaced apicobasal ridges restricted to one surface of the tooth and the triangular or approximately triangular cross section of the crown are other features shared between MSNC 4475 and Makhaira rossica. Differences between these two specimens are also present: the apicobasal ridges are not located on the curved side in the large tooth of Makhaira rossica (but such ridges are present in one small replacement tooth (figure 3) and thus possibly variable with dental development in Makhaira rossica), and the weak development of a trihedral cross section in the Sicilian tooth. It is not currently possible to make a definitive statement on the affinities of MSNC 4475, which clearly is an important specimen and potentially illustrates the profound convergence of Makhaira rossica with macrophagous archosaurs. However, future discoveries are likely to clarify whether MSNC 4475 is a late-surviving, low-latitude metriorhynchid or a brachauchenine pliosaurid.

Valentin Fischer, Maxim S. Arkhangelsky, Ilya M. Stenshin, Gleb N. Uspensky, Nikolay G. Zverkov and Roger B. J. Benson. 2015. Peculiar Macrophagous Adaptations in A New Cretaceous Pliosaurid. Royal Society Open Science. DOI: 10.1098/rsos.150552

twitter.com/pantheo27705718/status/680044196632252416

[Paleontology • 2016]

Sirindhorna khoratensis | สิรินธรน่า โคราชเอนซิส • A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand

สิรินธรน่า โคราชเอนซิส | Sirindhorna khoratensis Shibata, Jintasakul, Azuma & You, 2015

Fig 16. Skull of Sirindhorna khoratensis. (A) A composite skull reconstruction of Sirindhorna. Several elements are reversed. (B) Life restoration of the head of Sirindhorna by Yoko Ohnish.

Scale bar equals 10 cm. Dashed line indicates missing elements.

DOI: 10.1371/journal.pone.0145904

Abstract

A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.

Introduction

Fossil records of non-hadrosaurid hadrosauriform dinosaurs in Asia have been accumulated in this century. Although these discoveries mainly came from China and Mongolia, new findings have been known from Uzbekistan, Kazakhstan, Japan and Thailand. However, well-preserved iguanodontian specimens were restricted in China and Mongolia; for instance, Jinzhousaurus yangi was known as the almost complete articulated skeleton found from Liaoning Province, Xuwulong yueluni was represented by an articulated skeleton without appendages from Gansu Province of China, and Probactrosaurus gobiensis from Inner Mongolia was described including several individuals of cranium and post cranial portions. In contrast, although two iguanodontians known from the Lower Cretaceous of Thailand, Siamodon (maxilla and referred braincase) and Ratchasimasaurus (dentary), none of them provides enough characters to discuss their phylogenies in detail. The new taxon in this study is known from extensive remains including a disarticulated skull and mandibles, and is much more complete than material of the aforementioned Thailand iguanodontians. This new material was collected from one locality of the Lower Cretaceous Khok Kruat Formation during the first term of Japan-Thailand Dinosaur Project (abbreviated as JTDP), including the preliminary excavation by NRRU in 2005. We describe this material and discuss its phylogenetic position based on a cladistic analysis.

Fig 1. Locality map and stratigraphic column for Sirindhorna.
(A) Map of Nakhon Ratchasima Province, Thailand, (B) localities of Sirindhorna (star mark), Ratchasimasuarus (R) and Siamodon (S), (C) stratigraphic column for the Khorat Group.

DOI: 10.1371/journal.pone.0145904

Fig 3. Photo (A) and line drawing (B) of the left lateral side of the skull (NRRU3001-166).

DOI: 10.1371/journal.pone.0145904

Systematic Paleontology

Dinosauria Owen, 1842

Ornithischia Seeley, 1887

Iguanodontia Dollo, 1888 sensu Sereno, 2005

Ankylopollexia Sereno, 1986 sensu Sereno, 2005

Styracosterna Sereno, 1986 sensu Sereno, 2005

Hadrosauriformes Sereno, 1997 sensu Sereno, 1998

Hadrosauroidea Sereno, 1986 sensu Sereno, 2005

Sirindhorna gen. nov.

urn:lsid:zoobank.org:act:40C4FBA5-455F-45AE-AD5A-33B6A6FB8723

Sirindhorna khoratensis, sp. nov.

urn:lsid:zoobank.org:act:54C342F2-EB92-4047-8F78-714025579CB5

Etymology: Dedication to the Princess Maha Chakri Sirindhorn, Thailand, for her contribution to the support and encouragement of paleontology in Thailand. The specific name comes from the name of the locality, Khorat, which is the informal name of Nakhon Ratchasima Province, northeastern Thailand.

Diagnosis: Basal hadrosauroid distinguished by an autapomorphy: sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture, and the following unique combination of characters: relatively straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, antorbital fossa of the maxilla not visible, slightly rostrally deepening dentary ramus, simple troughs for dentary alveoli with vertical walls and tooth crown-shaped base, vertical coronoid process expanded along rostral and caudal margins, and dentary teeth with primary and secondary ridges but no accessory ridges.

Holotype: An articulated braincase comprising the supraoccipital, exoccipitals, opisthotics, prootics, parietals, frontals, basioccipital, basisphenoid orbitosphenoids, parasphenoid and laterosphenoids, with postorbitals and squamosals (NRRU3001-166)

Referred materials: Disarticulated elements of skull and mandibles: a braincase articulating with a left postorbital (NRRU-A2035), dorsal half of a braincase (NRRU3001-65), caudal portion of a braincase (NRRU3001-179), a right premaxilla (NRRU-A3623), a left maxilla (NRRU-A2048), a right maxilla (NRRU-A2047), a right jugal (NRRU3001-7), a right quadrate (NRRU3001-175), a predentary (NRRU3001-169), a left dentary (NRRU3001-14), a right dentary (NRRU3001-167), a right surangular (NRRU3001-137), isolated maxillary teeth (NRRU-A1956, A3630, A3649, NRRU3001-157, 163), an isolated dentary tooth (NRRU3001-28).

Locality and horizon: In Ban (meaning “village”) Saphan Hin, Suranaree Subdistrict, Muaeng Nakhon Ratchasima District, Nakhon Ratchasima Province, Thailand. Lower Cretaceous (Aptian) Khok Kruat Formation.

Fig 15. Comparisons with other Thailand iguanodontians.
(A) Holotypic left maxilla of Siamodon, (B) holotypic right dentary of Ratchasimasaurus, (C) left maxilla of Sirindhorna (NRRU-A2048), (D) left dentary of Sirindhorna (NRRU3001-167).

Scale bars equal 10 cm. DOI: 10.1371/journal.pone.0145904

Conclusions

The Early Cretaceous hadrosauroid dinosaur, Sirindhorna khoratensis, is described based upon cranial elements. This is the first report of well-preserved ornithopod skull in Southeast Asia (See reconstruction, in Fig 16). Sirindhorna shows general morphological features of hadrosauriforms, such as the low-triangle shaped maxilla, a broad leaf-shaped dentary tooth crown with one prominent primary and one secondary ridges, exclusion of the supraoccipital from the foramen magnum, and the closure of the antorbital fenestra. Uniquely, the craniocaudally-elongated parietals form a long saggital crest extending to the frontoparietal suture in Sirindhorna. Moreover, upper and lower jaws of Sirindhorna show evident differences from the other two Thailand hadrosauriforms, Siamodon nimingami and Ratchasimasaurus suranareae. Phylogenetic analysis recovers Sirindhorna as the most basal hadrosauroid.

Masateru Shibata, Pratueng Jintasakul, Yoichi Azuma and Hai-Lu You. 2015. A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand. PLoS ONE. 10 (12): e0145904. DOI: 10.1371/journal.pone.0145904

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โดยความร่วมมือของคณะสำรวจไทยจาก มหาวิทยาลัยราชภัฏนครราชสีมา [Nakhon Ratchasima Rajabhat University: NRRU] และพิพิธภัณฑ์ไดโนเสาร์จังหวัดฟุกุอิ [Fukui Prefectural Dinosaur Museum] ประเทศญี่ปุ่น ได้ศึกษาและขุดค้นภาคสนามที่ตำบลสุรนารี อำเภอเมืองนครราชสีมา จังหวัด นครราชสีมา ในชั้นตะกอนหินกรวดสีแดง ในหมวดชั้นหินโคกกรวด ซึ่งเป็นชั้นตะกอนหินที่ก่อตัวในช่วงต้นยุคครีเตเชียสเมื่อประมาณ 110 ล้านปีก่อน

การขุดค้นพบครั้งนี้ได้พบชิ้นส่วนฟอสซิ ลกระโหลกของไดโนเสาร์กินพืชกลุ่มออร์นิโธพอด ชิ้นกระดูกส่วนท้ายทอย ปลายจะงอยปากบน และกรามล่าง ซึ่งจากการศึกษาลักษณะเอกลักษณ์นั้น ฟอสซิลของไดโนเสาร์ตัวใหม่นี้มีลักษณะบางประการที่ดูคล้ายคลึงกับไดโนเสาร์ ในกลุ่มอิกัวโนดอน แต่มีลักษณะของปลายจะงอยปากทรงสามเหลี่ยมแบนที่เป็นลักษณะของกลุ่มฮาโดรซอร์ ที่พัฒนาขึ้น

. . . การค้นพบนี้คณะวิจัยได้ขอพระราชทานชื่อสายพันธุ์ไดโนเสาร์ชนิดใหม่นี้จาก สมเด็จพระเทพรัตนราชสุดาฯ สยามบรมราชกุมารี เพื่อเฉลิมพระเกียรติ โดยไดโนเสาร์สายพันธุ์นี้มีชื่อวิทยาศาสตร์ว่า สิรินธรน่า โคราชเอนซิส (Sirindhorna khoratensis) ซึ่งชื่อสายพันธุ์นั้นได้ใช้คำว่า โคราช ชื่อเดิมของจังหวัดนครราชสีมา

สิรินธรน่า เป็นไดโนเสาร์กินพืชในกลุ่มฮาโดรซอร์ที่มีลักษณะโบราณมาก ซึ่งอาศัยอยู่ในช่วงเวลาและหมวดหินที่ใกล้เคียงกันอย่างไดโนเสาร์สายพันธุ์ สยามโมดอน (Siamodon nimingami) และราชสีมาซอรัส (Ratchasimasaurus suranareae) แม้ว่าการศึกษาจะระบุว่าสองสายพันธุ์ที่กล่าวมาจะอยู่ในกลุ่มอิกัวโนดอนมากกว่า

ฮาโดรซอร์ หรือไดโนเสาร์ปากเป็ดเป็นกลุ่มไดโนเสาร์กินพืชที่พัฒนาขนาดให้ใหญ่ขึ้นมากใน ช่วงปลายยุคครีเตเชียส ซึ่งเป็นหนึ่งในกลุ่มไดโนเสาร์กินพืชที่อาศัยอยู่ในภูมิภาคซีกโลกเหนืออย่าง เอเชีย-ยุโรป และอเมริกาเหนือ และสูญพันธุ์ในช่วงปลายยุคครีเตเชียส

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quarta-feira, 6 de janeiro de 2016

Os novos elementos da tabela periódica

Leia texto de professor do Instituto de Química da Unesp em Araraquara

[05/01/2016]

Todas salas de aula do Instituto de Química da Unesp em Araraquara têm pendurada na parede a Tabela Periódica. Como uma espécie de brincadeira, sugerimos aos estudantes reverenciar aquela figura, sempre que entrarem na sala para uma aula. A brincadeira obviamente se refere ao ato de reverência. Mas talvez não fosse uma má ideia reverenciá-la. Afinal de contas, é a maior “obra de arte” construída pelos seres humanos. Por centenas deles, trabalhando durante centenas de anos!

Lá estão todos elementos químicos do universo. Organizados em períodos (linhas horizontais) e grupos (linhas verticais). A aventura, ou história, da Tabela Periódica é fascinante e merece ser lida (veja, por exemplo: Alguns aspectos históricos da classificação periódica dos elementos químicos, Mario Tolentino e Romeu C. Rocha-Filho, Química Nova 20(1), 103-117, 1997).

Seu formato foi evoluindo ao longo dos anos e seu formato atual apresenta os elementos químicos em ordem crescente de número atômico. Este formato é particularmente interessante porque, além de possibilitar classificar os elementos em termos de propriedades físicas e químicas (o que faz dela uma ferramenta muito útil), permite prever a existência ou síntese de novos elementos.

É aí que entram os fatos noticiados no último dia 30 de dezembro pela IUPAC (União Internacional de Química Pura e Aplicada). Foram descobertos os elementos que faltavam para completar o período de número 7 (com números atômicos 113, 115, 117 e 118). Grupos de pesquisa no Japão, Rússia e Estados Unidos, trabalhando em laboratórios de aceleradores de partículas e fusão nuclear, conseguiram comprovar a síntese.

Uma vez sintetizados, este elementos pesados têm existência efêmera de milésimos de segundo. Aplicação prática imediata? Nenhuma. De fato, elementos sintéticos podem ter aplicações importantes. O Tecnécio, por exemplo (número atômico 43), tem aplicações importantes em medicina nuclear.

Mas não é o caso dos quatro novos elementos. Eles servem para completarmos nossas Tabelas e diminuir os espaços vazios. Este tipo de pesquisa vislumbra a síntese um dia, de um elemento mais pesado (período 8, 9, etc.) que possa ser estável e apresentar propriedades que permitam novas aplicações.

Os nomes dos quatro novos elementos ainda são provisórios. A IUPAC vai tratar de “batizá-los” formalmente no futuro.

Sidney José Lima Ribeiro é professor do Instituto de Química da Unesp de Araraquara

A era de ouro dos cinodontes

Espécie descoberta primeiro na África e agora no Brasil viveu durante o auge da diversidade dos animais precursores dos mamíferos

IGOR ZOLNERKEVIC | ED. 238 | DEZEMBRO 2015

Paisagem do Triássico: à beira d’água, o cinodonte Menadon besairiei com filhotes, seguido por um bando de Santacruzodon hopsoni. À esquerda, um Dagasuchus santacruzensis, réptil carnívoro como o Chanaresuchus bonapartei (atrás da árvore).

Dezenas de milhões de anos antes de os dinossauros dominarem a Terra, reinava sobre os continentes uma fauna peculiar. Entre esses animais havia um grupo grande e diverso que guarda uma curiosa semelhança com os mamíferos atuais. Esses animais primitivos eram os cinodontes, grupo que começou a desenvolver as características que hoje são exclusivas dos mamíferos: sangue quente, pelos sobre o corpo e diferentes tipos de dentes na boca – em latim, cinodonte significa dentes de cão.

Por um longo período, havia em todos os continentes cinodontes carnívoros e herbívoros, como o Menadon besairiei, que vigia seus filhotes na ilustração destas páginas e, agora se sabe, também viveu onde hoje é o Sul do Brasil. Com cerca de 1 metro de comprimento (o tamanho de um cachorro grande), o Menadon possivelmente teria a aparência de um descendente do cruzamento impossível de um jacaré com capivara. Era um integrante da linhagem dos traversodontídeos, a mais diversa dos cinodontes e já extinta. Havia muitas outras linhagens e uma delas, a dos mamaliamorfos, deu origem aos mamíferos.

Os paleontólogos Tomaz Melo e Marina Soares, da Universidade Federal do Rio Grande do Sul (UFRGS), em colaboração com o paleontólogo argentino Fernando Abdala, da Universidade de Witwatersrand, África do Sul, descobriram que o Menadon besairiei, cujo fóssil foi primeiramente encontrado em rochas da Ilha de Madagascar, na costa leste da África, também viveu na mesma época, há cerca de 230 milhões de anos, na região que hoje ocupa o interior do Rio Grande do Sul. O Menadon existiu, portanto, em meados do chamado período Triássico, entre 250 milhões e 200 milhões de anos atrás, quando América do Sul, África (Madagascar inclusa) e os demais continentes estavam unidos em um único supercontinente, a Pangeia.

Crânio de Menadon besairiei achado no Rio Grande do Sul: o animal tinha cerca de 1 metro de comprimento e integrava a linhagem dos traversodontídeos.

O estudo, publicado on-line em setembro no Journal of Vertebrate Paleontology, confirma que traversodontídeos como o Menadon povoaram a Pangeia de uma ponta a outra. “A maioria dos fósseis de traversodontídeos foi encontrada na América do Sul e no sul da África, mas também há registros na América do Norte e na Europa”, explica Marina, que orientou Melo em seu mestrado sobre o Menadon na UFRGS. “Como não havia grandes barreiras geográficas à fauna na Pangeia, os traversodontídeos e outros grupos de animais da época tinham essa distribuição cosmopolita.”

De santa cruz a madagascar

Abdala, considerado um dos principais especialistas em cinodontes no mundo, já havia notado em 2001 uma semelhança entre a fauna fossilizada de uma camada de rochas areníticas que aflora no município de Santa Cruz do Sul, no Rio Grande do Sul, e a fauna fóssil da camada rochosa de Isalo II, encontrada em Madagascar e descrita por paleontólogos norte-americanos em 2000. Um dos traversodontídeos descobertos em Isalo II, o Dadadon isaloi, lembrava muito o Santacruzodon hopsoni, encontrado em Santa Cruz do Sul (ele aparece na ilustração atrás do Menadon nas páginas 60 e 61). Da mesma forma, o Menadon besairiei apresentava semelhanças com o crânio de uma espécie encontrada em Santa Cruz, mas que ainda não havia sido identificada.

Coube a Melo esclarecer a questão no seu mestrado, comparando o crânio descrito por Abdala com materiais adicionais – mais crânios, pedaços de mandíbula e alguns fragmentos de ossos do corpo – da espécie não identificada, coletados posteriormente no mesmo local e preservados por pesquisadores da UFRGS e da Fundação Zoobotânica do Rio Grande do Sul. “Podia ser uma espécie muito próxima, mas ao final da análise não encontramos nenhuma diferença entre ela e o Menadon besairiei”, explica Melo, que está na metade de seu doutorado sobre os traversodontídeos, orientado por Marina. “Deve ser a mesma espécie de Madagascar.”

Botucaraitherium belarminoi: cinodonte carnívoro um pouco maior que um rato…

A descoberta ajuda a encaixar melhor duas peças do quebra-cabeças geológico que os paleontólogos precisam montar para reconstituir a história da vida no Triássico. “Nem todos locais do mundo têm rochas preservadas de uma mesma idade”, explica Marina. A semelhança entre as faunas fósseis do Rio Grande do Sul e de Madagascar, grande a ponto de compartilharem uma espécie, confirma que as camadas de arenito de Santa Cruz do Sul e de Isalo II devem ter quase a mesma idade, entre 232 milhões e 228 milhões de anos, as únicas rochas sedimentares com essa idade preservadas na América do Sul e na África. “Cada novo achado permite reforçar correlações temporais entre as camadas de rocha de diferentes partes do mundo.”

Há lacunas na história do Triássico em todos os continentes. No sul da África, por exemplo, os paleontólogos já identificaram rochas sedimentares que se formaram a partir de lama ou areia no final e no início do período, mas não há rochas preservadas do meio do período, como acontece na Argentina e no Brasil.

...dotado de dentes pontiagudos (acima), adaptados a uma dieta à base de insetos

…dotado de dentes pontiagudos, adaptados a uma dieta à base de insetos.

Melo explica que é raro os pesquisadores conseguirem datar a idade das rochas sedimentares do Triássico de maneira absoluta. Algumas camadas da Argentina, por exemplo, foram datadas por meio do decaimento de isótopos radiativos de cinzas vulcânicas. “Mas, em geral, dependemos da comparação dos fósseis encontrados em camadas diferentes para saber se possuem a mesma idade”, diz Melo.

Para determinar as idades relativas das camadas de rochas, os pesquisadores usam em geral comparações entre fósseis microscópicos como grãos de pólen e esporos de pteridófitas, que são abundantes em todas as épocas. “Nosso problema é que as rochas do Triássico do Rio Grande do Sul se depositaram em margens de rios e planícies de inundação, ambientes bem aerados”, Melo explica. “O oxigênio acabou com o pólen e os esporos. A única maneira de datar as rochas é por meio dos fósseis de vertebrados.”
O grupo de cinodontes que mais se diversificou em meados do Triássico foi o dos traversodontídeos. Diferentes dos demais cinodontes, geralmente carnívoros ou onívoros, os traversodontídeos eram herbívoros, com dentes especializados para comer raízes, folhas ou qualquer outra matéria vegetal disponível no clima quente e semiárido que prevalecia no interior da Pangeia.

O carnívoro Trucidocynodon riograndensis, que chegava a 1,20 metro…

Competição entre herbívoros
Os traversodontídeos deviam competir por alimento com os outros grandes herbívoros da época: os dicinodontes, grupo aparentado dos cinodontes, mas sem características de mamíferos; e os rincossauros, que eram répteis. Os grandes predadores desses herbívoros eram os pseudossúquios, répteis semelhantes a crocodilos gigantes. Um dos pseudossúquios que viveram no Rio Grande do Sul foi também descoberto em rochas de Santa Cruz do Sul. É o Dagasuchus santacruzensis, descrito por Marcel Lacerda, da UFRGS, e colegas, em um artigo publicado este ano na revista PLoS One.
As camadas de rocha do Triássico mais jovens que as de Santa Cruz do Sul, porém, sugerem que todos os traversodontídeos conhecidos foram extintos muito antes de o período acabar. Outras espécies de cinodontes, no entanto, persistiram até o fim do Triássico, com formas extraordinárias como as do Trucidocynodon riograndensis, um cinodonte com caninos protuberantes, que tinha 1,20 metro de comprimento e possivelmente era carnívoro. Encontrado em 2009 em rochas de 220 milhões de anos do município de Agudo, também no Rio Grande do Sul, o esqueleto fóssil de Trucidocynodon é um dos esqueletos de cinodonte mais completos já descobertos.

…um dos mais completos esqueletos de cinodontes já encontrados no país.

Outro grupo interessante de cinodontes, encontrado apenas nas rochas do Triássico Superior (entre 230 milhões e 200 milhões de anos) da formação Santa Maria, Rio Grande do Sul, é composto de animais pequenos, com cerca de 10 centímetros de comprimento e dentes serrilhados, úteis para uma dieta à base de insetos. “Não existe outro grupo de cinodontes no mundo que seja tão parecido com um mamífero quanto os descobertos no Rio Grande do Sul”, afirma Marina.

Desses pequenos cinodontes conhecidos como mamaliamorfos, a espécie mais recentemente descrita por ela e seus colaboradores é o Botucaraitherium belarminoi, encontrado no ano passado no município gaúcho de Candelária. “Temos mais três novas espécies sendo analisadas”, conta Marina, que espera descobrir alguma espécie dos primeiros mamíferos, que surgiram no final do Triássico e devem ter convivido com os cinodontes. “Um dia vamos encontrar.”

Artigo científico

MELO, T. P.; ABDALA, F.; SOARES, M. B. The Malagasy cynodont Menadon besairiei (Cynodontia; Traversodontidae) in the Middle-Upper Triassic of Brazil. Journal of Vertebrate Paleontology. No prelo.