Judith Pardo-Pérez | Staatliches Museum für Naturkunde Stuttgart (original) (raw)

Papers by Judith Pardo-Pérez

A: articulated nasals in dorsal view. B: left nasal in lateral view. C: right supratempo... more A: articulated nasals in dorsal view. B: left nasal in lateral view. C: right supratemporal in dorsal view. D–F: supraoccipital magnified two times with respect to the other bones, in posterior view (D) and in left anterolateral (otic) view (E,F). Note the lateral wing of the nasal forming an overhang on the naris, the narial process of the nasal, the long and straight squamosal facet of the supratemporal, and the weakly arched shape of the supraoccipital. Abbreviations: avsc: impression of the anterior vertical semicircular canal; pvsc: impression of the posterior vertical semicircular canal; ut: utriculus.</p

A–C: A. densus (GLAHM 132588, holotype), in posterior view (A,B) and ... more A–C: A. densus (GLAHM 132588, holotype), in posterior view (A,B) and anterior view (C). D,E: A. densus (SNHM1284-R), in posterior view. F: Platypterygius australis (QMF14339), in posterior view redrawn from Kear <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Kear1" target="_blank">[58]</a>. G: Sveltonectes insolitus (IRSNB R269, holotype), in posterior view, from Fischer et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Fischer2" target="_blank">[34]</a>. H: Ophthalmosaurus icenicus (NHMUK R4522, mirrored), in posterior view, redrawn from Kirton <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Kirton1" target="_blank">[43]</a>. I: Ophthalmosaurus icenicus (NHMUK R2161), in posterior view, redrawn from Andrews <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Andrews2" target="_blank">[51]</a>. Abbreviations: amp: ampulla; avsc: impression of the anterior vertical semicircular canal; hsc: impression of the horizontal semicircular canal; M.a.m.e. facet: facet for attachment of musculus adductor mandibulae externus; sac: sacculus; ut: utriculus.</p

"The Tyndall Glacier is located within Torres del Paine National Park in Chilean Patagonia a... more "The Tyndall Glacier is located within Torres del Paine National Park in Chilean Patagonia and represents an exceptional Early Cretaceous ichthyosaur fossil area. In 2003 researchers from Stanford University found a fragmentary ichthyosaur skeleton in the banks of a river close to the Tyndall Glacier. After this discovery, several expeditions to this locality were made. During two field campaigns in the years 2009 and 2010, financially supported by the German research fundation DFG, 46 articulated and partially articulated ichthyosaur skeletons were discovered, comprising adults, juveniles, neonates and even females with embryos. The majority of ichthyosaur specimens preserve diagnostic features permitting their systematic identification. So far, a complete specimen of Platypterygius hauthali and ?Caypullisaurus bonapartei have been identified. Moreover, an isolated forefin that could represent a new species and another hitherto unknown specimen with anatomical characteristics from ichthyosaurs of Jurassic age, have been found. The ichthyosaurs are associated with ganoid and teleost fishes, as well as abundant belemnites. Ammonites and inoceramids are also frequent. Tree trunks partially encrusted and remains of land plants indicate a close shoreline, probably combined with a river that formed a submarine canyon. The enormous abundance of life is documented in Neptunian dykes full of belemnites and ichthyosaur bone fragments. The abundance of ichthyosaur skeletons in the Tyndall area suggests mass mortalities caused by mudflows, running at high speed through submarine canyons. Ichthyosaurs were captured by this mud flow or were sucked by it into the abyss. The bodies were deposited in an anoxic environment, where they were rapidly covered by sediment, which explains their excellent preservation. The finding potential of this site as well as the quality and quantity of specimens is unique to South America and may represent one of the best sites of Early Cretaceous ichthyosaurs. "

Posidonienschiefer Formation, lower Toarcian. a. Complete skeleton in... more Posidonienschiefer Formation, lower Toarcian. a. Complete skeleton in dorsal (skull) and ventral view (postcranium). b. Left forefin indicating the pathological elements in the black circle. c. Arrow indicating the complete occlusion of the anterior notch of the radiale. Partial occlusion is also observed in the anterior notch of the radius, distal carpal two and metarcarpal two. Abbreviations: R: radius. ra: radiale. dc2: distal carpal two. mc2: metacarpal two.</p

Urwelt-Museum Oberfranken, Bayreuth, Germany; Rabold and Eggmaier (2013) specimen no. 14... more Urwelt-Museum Oberfranken, Bayreuth, Germany; Rabold and Eggmaier (2013) specimen no. 14. a. Overview of the skull exposed in ventral view, indicating the pathological areas in b, c, d and e. b. Posteriormost end of the right angular and surangular showing deformed, rugose tissue on the surangular and a deep pit in the angular. c. Long groove on the right ventrolateral margin of the right surangular. The margins are made of a crest of reactive bone. d. The same reactive bone crest in left ventrolateral view. e. Small protuberance of reactive bone on the ventral surface of the right splenial. f. Complete preserved skeleton in ventral view indicating the pathological portion of the right pectoral girdle. g. A broken fragment of premaxilla indicating the three areas with fibre remodeling with the white arrows. h. The pathological right coracoid, scapula, and humerus in ventral view, showing the pitting and the dorsoventral thickening compared with the elements of the left pectoral girdle. i-j. Two broken anterior dorsal ribs showing a rugose concavity at the distal end, which represents the proximal callus of a pseudarthrosis. Abbreviations: an, angular; d, dentary; hy, hyoid; ms, mandibular symphysis; pb, parabasisphenoid; pt, pterygoid; slp, sclerotic plates; sp, splenial; st p, stapes; su, surangular; v, vomer.</p

Measurements in cm of right and left pathologies observed in the premaxilla of UMH 454 (... more Measurements in cm of right and left pathologies observed in the premaxilla of UMH 454 (Temnodontosaurus trigonodon).</p

Frequency of preserved anatomical units of Temnodontosaurus.</p

Both specimens have incomplete vertebral series and the centra were therefore superposed... more Both specimens have incomplete vertebral series and the centra were therefore superposed manually in each region, using the centrum shape and relative position of the apophyses. Each obvious gap in the vertebral column is represented by a single void in the series of SNHM1284-R. The x-axis refers to the centrum count, not its actual position within the vertebral column. The regionalization of the vertebral column is quite weak, in between that of Sveltonectes insolitus <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Fischer2" target="_blank">[34]</a> and Ophthalmosaurus icenicus <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Massare1" target="_blank">[69]</a>.</p

A: survival (positive) and extinction (negative) rates in the conservative scenario, in ... more A: survival (positive) and extinction (negative) rates in the conservative scenario, in which post-Jurassic occurrences of both Ophthalmosaurus and Brachypterygius are ignored. B: survival (positive) and extinction (negative) rates in the total evidence scenario. C: cladogenesis rate. Light color represents phylogenetic lineages and dark color represents genera. Rates for the JCB are colored in orange. The JCB records high survival rates and low to null extinction rates, suggesting that no extinction took place amongst ichthyosaurs at the end of the Jurassic. Abbreviations: Apt: Aptian; Bar: Barremian; Ber, Berriasian; Hau: Hauterivian; Kim: Kimmeridgian; Oxf: Oxfordian; Tit: Tithonian.</p

A,B: basioccipital (LEICT G3.2001.001), in anterodorsal view (A) and posteroventral view... more A,B: basioccipital (LEICT G3.2001.001), in anterodorsal view (A) and posteroventral view (B). The basioccipital is sheared flat, giving the impression of a ‘Liassic-grade’ basioccipital. C,D: left humerus (LEICT G1.2001.016), in dorsal view (C) and ventral view (D). Abbreviation: aae facet: facet for the anterior accessory element; dpc: deltopectoral crest; eca: extracondylar area; exf: exoccipital fact; fm: median concavity for the foramen magnum.</p

Acamptonectes densus (GLAHM 132588, SNHM1284-R, NHMUK R11185), <i&... more Acamptonectes densus (GLAHM 132588, SNHM1284-R, NHMUK R11185), Acamptonectes sp. (CAMSM B57942), and cf. Ophthalmosaurus (LEICT G1.2001.016).</p

A–C: basioccipital (CAMSM B57962) in posterior view (A), dorsal view (B), and posteroven... more A–C: basioccipital (CAMSM B57962) in posterior view (A), dorsal view (B), and posteroventral view (C), showing the important extracondylar area (delimited by the broken line). The specimen is the only one of the Cambridge Greensand Formation to exhibit a bilobed concavity for the foramen magnum. D,E; basisphenoid (NHMUK R2341) in lateral (view (D) and posterior view (E), showing the facialis nerve foramen posterior to the basipterygoid process and the pentagonal posterior surface because of the dorsal crest that is characteristic for the genus. Abbreviation: bpp: basipterygoid process; eca: extracondylar area; fm: bilobed concavity for the foramen magnum; VII: foramen for the facialis nerve (VII).</p

A: coracoids and scapulae of SNHM1284-R in ventral view. B: Outline of the cross-section... more A: coracoids and scapulae of SNHM1284-R in ventral view. B: Outline of the cross-section of the scapula, showing its flattened shape. C: right scapula of GLAHM 132588 (holotype), in ventral view. D: lateral surface of the right coracoid of SNHM1284-R. E,F: comparison of the medial surface of the right scapula of SNMM1284-R (E) and of GLAHM 132588 (holotype; F).</p

A: A. densus (GLAHM 132588, holotype), in posterolateral view showing... more A: A. densus (GLAHM 132588, holotype), in posterolateral view showing the lateral ridge. B,C: A. densus (SNHM1284-R), in ventral view showing the peculiar thickened lateral foot. D,E: A. densus (GLAHM 132588, holotype), in otic (anteromedial) view. F,G: A. densus (SNHM1284-R), in otic view. H: Ophthalmosaurus icenicus (NHMUK R4523), in otic view, redrawn from Kirton <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Kirton1" target="_blank">[43]</a>. I: Platypterygius australis (AM F98273), in otic view, redrawn from Kear <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Kear1" target="_blank">[58]</a>. J: Mollesaurus periallus (MOZ 2282, holotype), in otic view, redrawn from Fernández <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029234#pone.0029234-Fernndez3" target="_blank">[45]</a>. Abbreviations: amp: ampulla; bof: basioccipital facet; hsc: impression of the horizontal semicircular canal; pvsc: impression of the posterior vertical semicircular canal; sac: sacculus; ut: utriculus; vag: vagus foramen.</p

Posidonienschiefer Formation (lower–middle Toarcian). a. Complete ske... more Posidonienschiefer Formation (lower–middle Toarcian). a. Complete skeleton prepared in left lateral view indicating the pathological areas in the skull (b) and ribs (g). b. Skull, indicating the detected pathologies of the left premaxilla, maxilla and dentary in c, d, e and f. c. Detail of the fibre remodeling observed in the premaxilla indicated in the black circles. d, e. Arrows indicating remodeled areas on the lateral surface of the premaxilla. f. Left dentary indicating two areas with fibre remodeling on the anteroventral edge. g. left lateral view of the left and right (h) dorsal ribs indicating the broken and healed ribs with the black circles. h. Detail of the broken and healed right dorsal ribs.</p

Examples of pathological vs non-pathological bone modifications in Temnodontosa... more Examples of pathological vs non-pathological bone modifications in Temnodontosaurus.</p

Numismalismergel Formation (lower Pliensbachian). a. Skull in dorsal ... more Numismalismergel Formation (lower Pliensbachian). a. Skull in dorsal view indicating the pathologies in the premaxilla in b, c and d. b. Right premaxilla showing two areas of fibre remodeling (inset: magnified view). c. Lateral surface of the right premaxilla indicating five small areas of fibre remodeling. d. Dorsal view of the right and left premaxillae, indicating areas with fibre remodeling. e. Skull in left lateral view indicating pathological areas on the left premaxilla (f) and left dentary (g). f. Three small areas with fibre remodeling on the left premaxilla. g. Fibre remodeling on the ventrolateral margin of the left premaxilla and the lateral surface of the left dentary. h. Skull in ventral view, showing the location of the pathologies illustrated in i-n. i. A posteroventral to anterodorsally oriented concavity in the right angular. The arrows indicate slight fibre remodeling at the ends. j. A rugose protuberance with fibre remodeling on the right splenial. k. Pathological area between the left angular and surangular demarcated by dotted lines. l. A small area with callus development on the left angular. m. Three small protuberances with fibre remodeling on the lateral margin of the left angular. n. A teardrop concavity between the left angular and left surangular with fibre remodeling at its dorsal and ventral corners.</p

Posidonienschiefer Formation, ?lower Toarcian. a. Skull exposed in le... more Posidonienschiefer Formation, ?lower Toarcian. a. Skull exposed in left lateral view showing pathologies on the premaxilla, nasal and dentary in b-g. b. Rugose area with fibre remodeling on the lateral surface of the premaxilla. c. Fibre remodeling on the ventrolateral margin of the premaxilla indicated with white arrows. d. Rugose-textured remodeled area on the posterodorsal surface of the premaxilla. e. Tissue remodeling on the dorsal surface of the nasal. f-g. Fibre remodeling on the lateral surface of the left dentary: f. at the level of the symphysis; g. at the dorsolateral margin.</p

Proceedings of the Zoological Institute RAS

An ichthyosaurian skeletal remains assigned to the genera Arthropterygius and Ophthalmosaurus are... more An ichthyosaurian skeletal remains assigned to the genera Arthropterygius and Ophthalmosaurus are described from the Volgian deposits of the Komi Republic and Nenets Autonomous Region (Okrug) (Russia). These specimens along with findings from Svalbard provide an opportunity to draw some preliminary conclusions on the distribution of ichthyosaurs during the Late Jurassic and Early Cretaceous epoch.

Frequency of preserved anatomical units of Temnodontosaurus.</p

Examples of pathological vs non-pathological bone modifications in Temnodontosa... more Examples of pathological vs non-pathological bone modifications in Temnodontosaurus.</p

Proceedings of the Zoological Institute RAS

During the Late Jurassic, important palaeogeographic events occurred in Eurasia, North America an... more During the Late Jurassic, important palaeogeographic events occurred in Eurasia, North America and Gondwana. Continental rift, subduction and orogeny produced different levels of marine inundation of terrestrial systems, with rising sea level. Shallow epicontinental seaways started to separate North America from Eurasia, Gondwana, and also between segments of Gondwana itself. Tethys, the east-west seaway, expanded and at times covered large parts of the continental interior of Eurasia. The aperture of new seaways such as the Greenland-Norwegian seaway and the Mezen-Pechora strait system in the northern hemisphere; the Hispanic Corridor, between North and South America; and the Trans-Erythrean seaway (or South Africa/Rocas Verdes seaway) in the southern hemisphere allowed for intermittent interchange of invertebrate and marine vertebrate faunas.
During the past five years, the ichthyosaur fossil record has provided a way to describe new species so as to complement diagnoses of species that for a long time had been either synonymised or considered invalid. These taxonomic studies allow us now to understand the paleo-distribution of the ichthyosaurs around the world better as the relationships between the realms of the northern-southern hemisphere and boreal regions. The present report is a generic-level analysis of the dispersal routes of ichthyosaurs during the Late Jurassic compared with one of its top predators, Pliosaurus, and the palaeogeographic significance of high-latitude species such as Arthropterygius spp., Undorosaurs spp., Cryopterygius spp, Janusaurus and non-ubiquitous ichthyosaurs.

The Tyndall Glacier in the Torres del Paine National Park is an extremely fossiliferous area of ... more The Tyndall Glacier in the Torres del Paine National
Park is an extremely fossiliferous area of the Chilean
Patagonia. In this area numerous articulated and a few
complete ichthyosaurs were found. Most individuals
are adults and juveniles. However, a few neonates and
females with embryos also occur. The ichthyosaur
skeletons are associated with abundant belemnites,
ammonites and inoceramid bivalves. Ganoid and
teleost fishes are frequently found. The record of tree
trunks and remains of land plants suggest an environment
in close vicinity to the shore.
The meltdown of Tyndall Glacier has exposed sedimentary
rocks in an area of about 10 km2, which are part of the Zapata Formation (?145–99 Ma). During the field campaign of 2009 to Torres del Paine National Park, a complete, isolated forefin of a platypterygian ichthyosaur was discovered. The specimen
represents one of the best‐preserved Platypterygius forefins from the Early Cretaceous and shows some features that are not preserved in other Platypterygius species. Nevertheless, some factors such as the small number of Platypterygius specimens that has been found (McGowan, 1972; Fernández and Aguirre‐
Urreta, 2007; Arkhangelsky et al., 2008), their incompleteness
and, in consequence, the difficulty to judge the factor of morphological variability make an accurate and correct taxonomic identification difficult.
The high amount of specimens and the good preservation
of the Tyndall ichthyosaurs is thus crucial for the understanding of the diversity of paleocommunities of ichthyosaurs during the Early Cretaceous and may represent one of the most informative areas for Early Cretaceous ichthyosaurs in the world.

Durante dos campañas de terreno al Glaciar Tyndall, en el Parque Nacional Torres del Paine, entre... more Durante dos campañas de terreno al Glaciar Tyndall, en el Parque Nacional Torres del Paine, entre los años 2009 y 2010, se han registrado 46 especímenes de ictiosaurios, muchos de
los cuales se han preservado semi-articulados y otros articulados y completos. Los individuos corresponden a ejemplares adultos, juveniles, algunas crías y embriones. La mayoría de los
especímenes presenta características diagnósticas que han permitido su identificación taxonómica. Hasta el momento se han reconocido cuatro especies diferentes de ictiosaurios:
Platypterygius hauthali (v. Huene), Platyperygius sp. nov. (en preparación), ?Caypullisaurus bonapartei Fernández, y un representante nuevo de ophtalmosaurio. Esta diversidad de especies es muy significativa para la comprensión de las paleocomunidades de ictiosaurios durante el
Cretácico Inferior. Además, los análisis taxonómicos y paleobiogeográficos en curso, de esta área, arrojarán nuevos datos sobre la historia evolutiva de los ictiosaurios cretácicos antes de su extinción, a comienzos del Cretácico Superior.
La abundancia de esqueletos casi completamente articulados sugiere mortalidades masivas causadas por flujos de lodo, que descendieron a gran velocidad a través de un cañón
submarino. Los ictiosaurios, al ser capturados en vida por este flujo, fueron succionados y
transportados hacia el fondo; muchos cuerpos se fracturaron producto de los golpes, al ser arrastrados, y finalmente murieron ahogados. Los cadáveres se depositaron en un ambiente
anóxico y fueron rápidamente cubiertos por sedimento, lo que explica su excelente grado de preservación.
El alto potencial de hallazgo de ictiosaurios que posee esta localidad, en el Parque Nacional Torres del Paine, así como su calidad de preservación, son únicos para Sudamérica y la
sitúan como uno de los principales yacimientos de vertebrados marinos a nivel mundial.

The Early Cretaceous ichthyosaurs graveyard at the Tyndall Glacier in the Parque Nacional Torres ... more The Early Cretaceous ichthyosaurs graveyard at the Tyndall Glacier in the Parque Nacional Torres del Paine, South Chile, is an outstanding locality both nation and worldwide. During two field campaigns in the years 2009 and 2010 40 articulated and semi-articulated ichthyosaur skeletons were discovered, comprising adults, juveniles, babies and embryos. The majority of the ichthyosaur specimens preserve diagnostic features permitting their identification to species level. Until now four different ichthyosaur species were identified in the field: Platypterygius hauthali (v. Huene, 1927) (Pardo et al. 2010 in preparation), ? Platypterygius platydactylus (Broili, 1907), ? Caypullisaurus bonapartei Fernández, 1997 and another hitherto unknown species that is different to the other three. This diversity is highly important for the understanding of the diversity in paleocommunities of ichthyosaurs during the Early Cretaceous. The taxonomic and the palaeobiogeographic analysis of the Tyndall ichthyosaur graveyard will throw new light on the evolutionary history of Cretaceous ichthyosaurs prior to their final extinction at the beginning of the Late Cretaceous. The abundance of near complete articulated ichthyosaur skeletons in the Tyndall area suggests mass mortalities caused by high-energy mudflows travelling down along submarine canyons. The ichthyosaurs were either caught directly by these mudflows or were dragged down into the abyss by the suction wave behind them. Their bodies ended up in an abyssal anoxic environment and were rapidly covered by fine sediment, which explains the excellent preservation.
The finding potential of the site as well as the quality of preservation and the quantity of specimens are unique for South America and place the Tyndall ichthyosaur locality among the best fossil sites for marine vertebrates worldwide.

The ichthyosaurs from the Torres del Paine National Park from the area of the Tyndall Glacier are... more The ichthyosaurs from the Torres del Paine National Park from the area of the Tyndall Glacier are embedded in radiolaritic mud- and sandstone turbidites with a hardness close to granite and an
enormous grain density. The site is difficult to access and requires minor climbing abilities. The climate is unpredictable and adds to the problems of an excavation under extreme conditions. In the years before data of the material exposed on the outcrop were collected directly in the field. During the field season in February we tested several methods to get single specimens out of the rock. The work turned out to be much more difficult than expected, especially due to the material properties of the
matrix and the fact that the bone is softer than the matrix and exceedingly brittle. Here we report on the specalties of the ichthyosaur site at the Tyndall glacier, failures and successes in the excavation attempts and the excavation methods we would like to apply during the next field trip, the success of
which is crucial for further investigations. We also report on the surprises that can happen and the experiences you can collect during several weeks camping in a nature reserve

In the year 2003, Shultz et al. reported the presence of a fragmentary ichthyosaur skeleton in th... more In the year 2003, Shultz et al. reported the presence of a fragmentary ichthyosaur skeleton in the Torres del Paine National Park in southern Chile. This find occurred in a large erratic block in glacio-fluvial sediments, adjacent to the Southern Patagonian Ice Field, and extended the distribution of ichthyosaurs some 1500 – 2000 km south of ichthyosaur material previously reported from the Neuquen basin in Argentina (e.g., Gasparini & Fernandez, 1997). In the years 2004 and 2005, however, expeditions to the area organized by glaciologists of the Universidad de Magallanes in Punta Arenas, located an outcrop area approximately 1 km to the east of the Shultz et al (2003) locality, where sediments similar to the isolated block contain numerous articulated ichthyosaur skeletons aligned with fragmentary material. These Torres del Paine National Park ichthyosaurs represent the southernmost occurrence of this group yet discovered in South America. At present, specimens are exposed to weathering and the fossil deposit and its faunal assemblage are virtually unknown.
In approximately one week of fieldwork in 2007, we discovered and relocated 15 completely or semi-articulated specimens of Ophtalmosauridae, including complete crania with teeth, vertebral columns with the tail bend preserved to the tiny terminal vertebrae, articulated flippers, girdles and thoracic elements. In addition,
primary fragments (e.g., vertebrae, ribs, isolated mandible) are abundant. The specimens reach a maximum length of 4.5 m, but most are between 3 and 4 m long. At least two juveniles were discovered with an approximate lenght of 50 cm.
The bones are black and thus easily recognized in the grey sandstone. Because all surfaces are polished by the retreating glacier, bones exposed on these surfaces are polished, too. But in most cases, large parts of the specimens are still embedded
and preserved in three dimensions. Our inicial on site analysis assigns the specimens to Platypterygius Von Huene, 1922 and cf. Caypullisaurus Fernández 1997. Regional geology and ammonites associated to the ichthyosaurs suggest that the assemblage is Hauterivian-Barremian in age.

Platypterygian ichthyosaurs recently discovered in the Torres del Paine National Park of Chile r... more Platypterygian ichthyosaurs recently discovered in the Torres del Paine National
Park of Chile represent the southernmost and stratigraphically youngest and most
complete specimens of this group worldwide. Within only one week of fieldwork
in February 2007, we located 15 articulated and subcomplete skeletons, both adults
and juveniles, associated with ammonites, belemnites, inoceramid bivalves and
teleostid fishes. The assemblage was deposited in monotonous siliciclastic flysch
lithologies of the now closed Rocas Verdes back-arc basin. This enormous concentration
of marine Mesozoic reptiles to present knowledge appears to be unique for
Chile and South America and will certainly place the locality among the prime
fossil lagerstätten for Jurassic-Cretaceous marine reptiles in the world. We have begun
to investigate taxonomy, biostratigraphy and palaeobiogeography of the Torres
del Paine ichthyosaurs and associated fossil assemblage. Our research further
aims to evaluate the conditions, which led to the excellent preservation and concentration
of marine vertebrates in this enigmatic fossil deposit.

Los ictiosaurios fueron reptiles marinos que poblaron los mares cálidos del Triásico temprano al ... more Los ictiosaurios fueron reptiles marinos que poblaron los mares cálidos del Triásico temprano al Cretácico inferior y Cenomaniano, siendo hasta la fecha considerados como los reptiles con mejor grado de adaptación a la vida en el mar, evidenciado por la amplitud geográfica de su registro. Sin embargo, los registros fósiles en Chile de estos reptiles marinos son pocos y el material es completamente fragmentario. El presente estudio presenta el resultado del análisis de diversos restos de fauna fósil, entre la que destaca la presencia in situ de ictiosaurios, amonites, belemnites y otros, en rocas de la Formación Zapata, en un área periglaciada del borde oriental del Glaciar Tyndall, en el Parque Nacional Torres del Paine. Los ejemplares de ictiosaurios registrados en esta área han sido asignados al género Platypterygius, basados en las características morfológicas de sus aletas. La edad que se determino para la secuencia estudiada es Hauteriviana-Barremiana, basada en la litología analizada en el perfil geológico, relacionado con lo propuesto por Wilson en el año 1991, para el miembro D de la Formación Zapata y la fauna amonoídea asociada al género Favrella. Estos hallazgos también permiten reforzar hipótesis que hacen mención acerca de una probable ruta sur en la trayectoria de estos reptiles marinos durante el Jurásico superior- Cretácico inferior.
Se agradece a la Dirección de Programas Antárticos, al Instituto Antártico Chileno y al Gobierno regional, por el apoyo logístico, económico y académico otorgado.

Como resultado de exploraciones realizadas en el área de Glacial Tyndall en el parque nacional To... more Como resultado de exploraciones realizadas en el área de Glacial Tyndall en el parque nacional Torres del Paine, personal de la Universidad de Magallanes (Chile) localizó varios esqueletos asignables a ictiosaurios. Los mismos han sido hallados en la Formación Zapata (Cretácico Inferior). Los ejemplares localizados corresponden a esqueletos articulados aunque incompletos. Entre ellos, hay dos particularmente significativos, un juvenil y un adulto, en los que se han
preservado caracteres diagnósticos que permiten referirlos al clado Ophthalmosauria. Este material representa el primer registro diagnosticable de ictiosaurios cretácicos de Chile. En el adulto se preservó la porción posterior de la columna vertebral y la aleta posterior derecha cuyos elementos constitutivos están completamente articulados. Esta aleta posterior es morfológicamente comparable a la del ictiosaurio del Titoniano-Berriasiano de la cuenca Neuquina
Caypullisaurus.

46 specimens of fully and partially articulated ichthyosaurs have been discovered during the fiel... more 46 specimens of fully and partially articulated ichthyosaurs have been discovered during the field campaigns of 2009 and 2010 in Early Cretaceous sediments located adjacent to the Tyndall glacier, in the northwest sector of Torres del Paine National Park in southern Chile. Four of these specimens were excavated and transported to Germany for preparation and documentation. However, the sediment turned out to be harder than the fossil bones and mechanical preparation was impossible. Application of hydrochloric and acetic acid methods was also hampered by the exceedingly low carbonate content of the bedrock. Therefore, we opted for the use of neutron imaging techniques as a third option to identify diagnostic morphological elements covered by sediment without destruction. The experiment was performed at the facility Neutra of the Paul Scherrer Institute in Villigen, Switzerland. The sections analyzed show cranial and postcranial features shared with other Tyndall specimens identified as Platypterygius von Huene. Here we report on the progress of our taxonomical analysis of the Tyndall ichthyosaurs.

Queda rigurosamente prohibida, sin la autorización escrita de los autores y del editor, bajo las ... more Queda rigurosamente prohibida, sin la autorización escrita de los autores y del editor, bajo las sanciones establecidas en la ley, la reproducción total o parcial de esta obra por cualquier medio o procedimiento, comprendidos la reprografía y el tratamiento informático. Todos los derechos reservados.

The Tyndall Glacier is located within Torres del Paine National Park in Chilean Patagonia and rep... more The Tyndall Glacier is located within Torres del Paine National Park in Chilean Patagonia and represents an exceptional Early Cretaceous ichthyosaur fossil area. In 2003 researchers from Stanford University found a fragmentary ichthyosaur skeleton in the banks of a river close to the Tyndall Glacier. After this discovery, several expeditions to this locality were made. During two field campaigns in the years 2009 and 2010, financially supported by the German research fundation DFG, 46 articulated and partially articulated ichthyosaur skeletons were discovered, comprising adults, juveniles, neonates and even females with embryos. The majority of ichthyosaur specimens preserve diagnostic features permitting their systematic identification. So far, a complete specimen of Platypterygius hauthali and ?Caypullisaurus bonapartei have been identified. Moreover, an isolated forefin that could represent a new species and another hitherto unknown specimen with anatomical characteristics from ichthyosaurs of Jurassic age, have been found.
The ichthyosaurs are associated with ganoid and teleost fishes, as well as abundant belemnites. Ammonites and inoceramids are also frequent. Tree trunks partially encrusted and remains of land plants indicate a close shoreline, probably combined with a river that formed a submarine canyon. The enormous abundance of life is documented in Neptunian dykes full of belemnites and ichthyosaur bone fragments.
The abundance of ichthyosaur skeletons in the Tyndall area suggests mass mortalities caused by mudflows, running at high speed through submarine canyons. Ichthyosaurs were captured by this mud flow or were sucked by it into the abyss. The bodies were deposited in an anoxic environment, where they were rapidly covered by sediment, which explains their excellent preservation.
The finding potential of this site as well as the quality and quantity of specimens is unique to South America and may represent one of the best sites of Early Cretaceous ichthyosaurs.

The Early Cretaceous ichthyosaurs graveyard at the Tyndall Glacier in the Parque Nacional Torres ... more The Early Cretaceous ichthyosaurs graveyard at the Tyndall Glacier in the Parque Nacional Torres del Paine, South Chile, is an outstanding locality both nation and worldwide. During two field campaigns in the years 2009 and 2010 46 articulated and semi-articulated ichthyosaur skeletons were discovered, comprising adults, juveniles, babies and embryos. The majority of the ichthyosaur specimens preserve diagnostic features permitting their identification to species level. Until now three
different ichthyosaur species were identified in the field: Platypterygius hauthali (v. Huene, 1927) (Pardo et al. 2010 in review), ?Caypullisaurus bonapartei Fernández, 1997 and a specimen of Platypterygius which have been preserved the forefin
complete but disjointed from the rest of his body. This specimen shows features that are not observed in Platypterygius species. Nevertheless, some factors such as the few amount of each species of Platypterygius, the poor state of conservation of most
of them and the morphologic variability among individuals of a population, which is in part determinated by environmental parameters; make difficult a certain and
complete taxonomic identification. The highly amount and well preservation of the Tyndall ichthyosaur graveyard is
tremendously important for the understanding of the diversity of paleocommunities of ichthyosaurs during the Early Cretaceous and will throw new lights on the evolutionary history of Cretaceous ichthyosaurs prior to their final extinction at the beginning of the Late Cretaceous. The abundance of near complete articulated
ichthyosaur skeletons in the Tyndall area suggests mass mortalities caused by high energy mudflows travelling down along submarine canyons. The ichthyosaurs were either caught directly by these mudflows or were dragged down into the abyss by the
suction wave behind them. Their bodies ended up in an abyssal anoxic environment and were rapidly covered by fine sediment, which explains the excellent preservation.

Los ictiosaurios fueron reptiles marinos pelágicos que poblaron los mares cálidos del Triásico al... more Los ictiosaurios fueron reptiles marinos pelágicos que poblaron los mares cálidos del Triásico al Cretácico. Se han encontrado fósiles en todo el mundo, lo que es un signo de su amplia migración. Evolucionaron de ancestros terrestres que volvieron al agua y fueron los reptiles que alcanzaron el mayor grado de adaptación al mar, llegando a ser vivíparos. Su cuerpo era fusiforme y presentaban una aleta dorsal y otra caudal. Respiraban aire, la configuración de su cráneo y mandíbulas se asemejaba a la de los reptiles, y tenían dos pares de extremidades.

Paleopathologies document ancient skeletal damage and can be used to infer the causes of injury, ... more Paleopathologies document ancient skeletal damage and can be used to infer the causes of injury, as well as aspects of related biology, ecology and behaviour. Few studies have been undertaken on Jurassic marine reptiles, and ichthyosaur pathologies in particular have never been evaluated at a generic level. Here we survey 51 specimens from the Early Jurassic of southern Germany that have been referred to the large macropredatory ichthyosaur Temnodontosaurus in order to document and analyse the frequency and type of pathologies. According to our analysis, most observed pathologies in Temnodontosaurus are injury-related traumas with signs of healing. Broken ribs are correlated with other pathological bone modifications in the skeleton, especially injuries to the skull. Observed cranial pathologies are similar to those reported for extinct cetaceans and mosasaurs, which have been interpreted as resulting from aggressive encounters with conspecifics. Unlike other marine amniote clades, Temnodontosaurus lack evidence of pathologies affecting the vertebral column. This may indicate functional differentiation of the axial skeleton in ichthyosaurs relative to other large secondarily aquatic apex-predators. The absence of avascular necrosis in the German material referred to Temnodontosaurus is notable and might reflect specific or population level variation in habitat relative to generic equivalents between the European epicontinental basins and England. This study is intended to document the type and frequency of pathologies in large ichthyosaurs occupying the ʽapex predatorʼ niche, and may provide a window into the behaviour of these animals when compared to other ichthyosaurs and marine tetrapods.