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some abstracts from Ameghiniana 41 (4)



Hi everyone, I thought it would be interesting to list
some of the abstracts so here they are,enjoy as I had
to skip some classes to photocopy this stuff lol

Mark Van Tomme



Alexander Wilhelm Armin KELLNER, New information on
the Tapejaridae (Pterosauria, Pterodactyloidea) and
discussion of the relationships of this clade,
AMEGHINIANA (Rev. Asoc. Paleontol. Argent.) - 41 (4):
521-534. Buenos Aires, 30-12-2004.

Abstract. A phylogenetic analysis indicates that the
Tapejaridae is a monophyletic group of pterodactyloid
pterosaurs, diagnosed by the following synapomorphies:
premaxillary sagittal crest that starts at the
anterior tip of the premaxilla and extends posteriorly
after the occipital region, large nasoantorbital
fenestra that reaches over 45% of the length between
premaxilla and squamosal, lacrimal process of the
jugal thin, distinct small pear­shaped orbit with
lower portion narrow, and broad tubercle at the
ventroposterior margin of the coracoid. Several
cranial and postcranial characters indicate that the
Tapejaridae are weIl nested within the Tapejaroidea,
in sister group relationship with the Azhdarchidae. A
preliminary study of the ingroup reIationships within
the Tapejaridae shows that Tupuxuara is more closely
related to Thalassodromeus relative to Tapejara. At
present tape­jarid remains have been found in the
following deposits: Crato and Romualdo members of the
Santana Formation (Aptian-Albian), Araripe Basin,
Brazil; Jiufotang Formation (Aptian), Jehol Group of
western Uaoning, China; and in the redbeds
(Cenomanian) of the Kem Kem region, Morocco. An
incomplete skull found in the Javelina Formation
(Maastrichtian), Texas also shows several tapejarid
features and might be a member of this clade. Although
information is stilllimited, the present distribution
of the Tapejaridae indicates that this clade of
pterosaurs was not exclusive of Gondwana, and was more
widespread than previously known.


Jorge O. CALVO, David RUBlLAR-ROGER, and Karen MORENO,
A new Abelisauridae (Dinosauria: Theropoda) from
northwest Patagonia, AMEGHINIANA (Rev. Asoc.
Paleontol. Argent.) - 41 (4): 555-563. Buenos Aires,
30-12-2004.

Abstract. A new theropod Abelisauridae is described,
Ekrixinatosaurus novasi gen. et sp. nov., of
north­westert Patagonia (Neuquén Province, Argentina).
A preliminar cladistic analysis placed
Ekrixinatosaurus together with Majungatholus and
Camotaurini; and the sister group is Ilokelesia.The
presence of this spec­imen in Albian-Cenomanian beds
allows us to support the early divergence
(pre-Senonian) of this clade,
. and the hypothesis of the presence of Abelisauridae
in continental Afrlca. The present distribution of
Abelisauridae indicates: 1) a vicariance of this clade
based on a pre-Cenomanian pan-Gondwanic distrib­ution;
2) dispersion throughout terrestrial bridges. ln both
cases, the absence ofAbelisauridae in conti­nental
Afrlca can be considered a bias of the fossil record.


Jorge O. CALVO, Juan D. PORFIRI, Claudio VERALLI,
Fernando NOVAS and Federico POBLETEI, Phylogenetic
status of Megaraptor namunhuaiquii Novas based on a
new specimen from Neuquén, Patagonia, Argentina,
AMEGHINIANA (Rev. Asoc. Paleontol. Argent.) - 41 (4):
565-5~5. Buenos Aires, 30-12-2004.

Abstract. A new specimen of Megaraptor namunhuaiquii
was discovered on the north coast of the Barreales
lake, Neuquén, Argentina. The material comes from the
Portezuelo Formation (Upper Turonian-Lower Coniacian)
of the Neuquén Group. The new specimen includes an
anterior cervical vertebra, scapula, cora­coïds, ulna,
radius, a complete hand, pubis, two caudal vertebrae
with haemal arch, and metatarsal IV. This finding
improves the knowledge of this species and offers more
information to elucidate its phylo­genetic
relationships. Megaraptor namunhuaiquii exhibits
resemblances with Carcharodontosauridae in some
aspects of the cervical and caudal vertebrae, but some
other similarities are seen with the basal
spin­osaurid Baryonyx in the shape of the scapula and
coracoid, and pubis shape with Torvosaunts. However,
Megaraptor bears several derived characters in the
construction of the forelimbs that clearly
distinguishes the Patagonian taxon from the theropod
taxa mentioned above.


Rodo1fo A. CORIA y Andrea B. ARCUCCI, Nuevos
dinosaurios teropodos de Auca Mahuevo, Provincia deI
Neuquén (Cretacico tardio, Argentina), AMEGHINIANA
(Rev. Asoc. Paleontol. Argent.) - 41 (4): 597-603.
Buenos Aires, 30-12-2004.

Abstract. NEW THEROPOD DINOSAURS FROM AUCA MAHUEVO,
NEUQUEN PROVINCE (LATE CRETACEOUS, ARGENTlNA).
Materials, of Theropoda from the upper levels of the
Anacleto Formation and the upper le­vels of the
underlaying Bajo de la Carpa Formation are described.
The specimens were collected from I1crocks outcropping
at Auca Mahuevo locality and surroundings, a
paleontological area from Neuquén Province that
yielded abundant remains of titanosaur eggs and
embryos. Some of the teeth were collected associated
with adult titanosaur bones, 'at the same levels that
bear titanosaur nests. These teeth have fea­tures
comparable with the dromeosaurid morphotype, and share
several characters with the teeth of the abelisaurid
Aucasaurus garridoi Coria et al., the only theropod
species described and illustrated from the l site.
Isolated postcranial material from the underlaying
Bajo de la Carpa Formation have been assigned to
theropod dinosaurs but lack Abelisauridae derived
features, being better linked with basal tetanuran
forms, with sizes comparable with those of
carcharodontosaurids.


Rubén MARTINEZ, Fernando NOVAS and Alfredo AMBROSI0,
Abelisaurid remains (Theropoda, Ceratosauria) from
southern Patagonia, AMEGHINIANA(Rev. Asoc. Paleontol.
Argent.) - 41 (4): 577-585. Buenos Aires, 30-12-2004.

Abstract. Here we report the discovery of abelisaurid
remains from the Bajo Barreal Formation
(Cenomanian-Coniacian) from the northem region of
Santa Cruz Province, Patagonia, Argentina. The
specimen represents the southemmost record of
Abelisauridae in South America. It consists of six
associ­ated vertebrae, inc1uding cervical 10, dorsal
1, an isolated dorsal centrum, and three caudals from
the rnid­die portion of the tail. The vertebrae
c1osely resemble those of other derived abelisaurids
(e.g., Carnotaurus sastrei Bonaparte, Alcasaurus
garridoi Coria et al.). For example, the cervicals
have deep pre- and postspinal cavities, hypertrophied
epipophyses, and a dorsal surface of the neural arch
that is c1early delirnited from the lateral surface of
the diapophysis. Caudal vertebrae exhibit the
characteristically fan-shaped trans­verse processes
seen in other abelisaurids. However, some
morphological distinctions are recognized when
compared with Ilok?lesia, Xenotarsosaurus,
Carnotaurus, AIcasaurus and Majungathollus. The list
of po­tential synapomorphies of the vertebral colurnn
of Abelisauria and Abelisauridae is briefly reviewed.
Recent phylogenetic hypotheses on Abelisauridae are
discussed.


Claudio VERALLI Y Jorge o. CALVO, Dientes de teropodos
carcharodontosauridos del turoniano
superior-Coniaciano inferior del Neuquén, Patagonia,
Argentina, AMEGHINIANA (Rev. Asoe. Paleontol. Argent.)
- 41 (4): 587-590. Buenos Aires, 30-12-2004.

Durante el ano 2000, un equipo de campo de la
Universidad Nacional deI Comahue descubrio el si­tio
Futalognko en la costa norte del lago Barreales,
Neuquén,. Argentina (Calvo et al., 2002). Desde
en­tones y hasta la fecha se desarrolla alli la
excavacion paleontologica mas larga llevada a cabo
hasta ahora en la Argentina. Como resuItado de esta
campana, se realizo una importante coleccion de
diferentes verte­brados deI Cretacico, que incluye mas
de 70 dientes de teropodos. Desafortunadamente, es muy
dificil asignar dien­tes de dinosaurios a géneros 0
familias, aUn asi, ellos tienen cierto grado de
utilidad taxon6mica. En gene­ral, solo los dientes de
teropodos pueden ofreeer crite­rios confiables para su
identificacion genérica y espe­cifica (Currie et al.,
1990; Ruiz Omenaca et al., 1997). En esta nota se
intenta identificar las relaciones de algu­nos dientes
del yacimiento Futalognko y se describen 5 dientes de
teropodos, caracterizados por presentar en los
mârgenes arrugas curvadas en el esmalte. Este caracter
es considerado una sinapomorffa de los
Carcharodontosauridae (sensu Sereno et al., 1996).


Karen MORENO , Nicolas BLANC0 y Andrew TOMLINSON,
Nuevas huellas de dinosaurios deI Jurasico Superior en
el norte de Chile, AMEGHINIANA (Rev. Asoc. Paleontol.
Argent.) - 41 (4): 535-543. Buenos Aires, 30-12-2004.
 

Abstract. NEW DINOSAUR FOOTPRINTS FROM THE UPPER
JURASSIC OF NORTHERN CHILE. Sauropod and theropod
footprints have been identified west of the city of
Calama, Region II of Chile, in red beds belonging to
the Estaci6n Member of the San Salvador Formation
(Kimmeridgian - Lower Cretaceous). Narrow-gauge
sauropod ichnites and three different morphologies of
theropod footprints are described: A) medium- to
large-sized tetradactyl impressions, with little
difference in size between digits II-IV, and a II-IV
interdig­ital angle of 66° and B) small- to
medium-sized tridactyl prints, with a marked
difference in size between dig­its III and II/IV, and
a II-IV interdigital angle of 85°; and C) a subaqueous
tridactyl print, probably made by only one foot of the
animal. The San Salvador tracksite is assumed to be
Upper Jurassic in age, because it is similar to other
tracksites of this period in lacking wide-gauge
sauropod footprints. This fact is prob­ably correlated
with the absence of titanosaurid body fossils in the
Jurassic of South America.


Jorge o. CALVO y Gerardo V. MAZZETIA, Nuevos hallazgos
de huellas de dinosaurios en la Formación Candeleros
(Albiano-Cenomaniano), Picún Leufú, Neuquén,
Argentina, AMEGHINIANA (Rev. Asoe. Paleontol. Argent.)
- 41 (4): 545-554. Buenos Aires, 30-12-2004.

Abstract. NEW FINDINGS OF DINOSAUR TRACKS lN THE
CANDELEROS FORMATION (ALBlAN-CENOMANIAN), PICÚN LEUFÚ,
NEUQUÉN, ARGENTINA. A new dinosaur tracksite is
described from the lower section of the Candeleros
Formation, Rio Umay Subgroup (Albian-Çenomanian). The
footprints were found on greyish, coarse to thin
sandstones from the Cerrito dei Bote islet, located at
the south-west end of Ezequiel Ramos Mexia
artificiallake, 15 km East .from Pietin Leuru.,
Neuquén, Argentina. The relatively good preservation
of the ichnosite allows to recognise three footprint
mor­photypes, corresponding to a middle-sized
titanosaurian sauropod, a large camosaurian theropod,
and a small coelurosaurian theropods. The titanosaur
footprints were referred to the ichnospecies
Sauropodichnus giganteus Calvo. The presence of
Abelichnus astigarrae Calvo was also documented
through two footprints belonging to a camosaur, and a
non previously registered footprint morphotype was
ascribed to coelurosaurs. The dinosaur speeds were
estimated from stride and footprint lengths of the
trackmakers. Footprint measurements were also used to
estimate the body masses of the trackmakers. The
ichnofauna studied shows, in ail cases, low speeds
that range from a maximum of 1.8 m S-1 for a
coelurosaur to a minimum of 0.9 m S-1 for the
titanosaur. The. analyses show that the dinosaurs
responsible for these trackways were either walking
(the titanosaur and the camosaur) or using a slow trot
gait (the coelurosaurs). Whichever the case, these
dinosaurs were progressing with gaits weil below their
potentiallocomotory capabilities. The overall
correspondence in direction and speed observed in the
tracks of the coelurosaurs is compatible with a social
pack-moving hypothesis.






        
                
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