| 1. |
- Novas, Fernando E., et al.
(författare)
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A new large pterosaur from the Late Cretaceous of Patagonia
- 2012
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Ingår i: Journal of Vertebrate Paleontology. - UK : Informa UK Limited. - 0272-4634 .- 1937-2809. ; 32:6, s. 1447-1452
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Tidskriftsartikel (refereegranskat)abstract
- Here, we expand the meager record of Late Cretaceous South American pterosaurs with the description of a partial rostrum belonging to a large azhdarchid pterodactyloid. The specimen was collected close to the Bajo de Arriagada locality, corresponding to the uppermost Cretaceous Allen Formation of Argentina, around 80 km northwest of the well-sampled Bajo de Santa Rosa locality. The specimen represents the first unambiguous evidence of an azhdarchid pterosaur from South America. This specimen represents a new genus and species, Aerotitan sudamericanus, which is diagnosed based ona unique combination of characters, including one autapomorphy,and represents one of the largest known South Americanpterosaurs. The fossil here described resulted from a joint Argentine-Swedish paleontological expedition to Patagonia.
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| 2. |
- Agnolin, Federico L., et al.
(författare)
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New alvarezsaurid (Dinosauria, Theropoda) from Latest Cretaceous of North-western Patagonia with associated eggs
- 2012
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Ingår i: Cretaceous research (Print). - : Elsevier BV. - 0195-6671 .- 1095-998X. ; 35, s. 33-56
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Tidskriftsartikel (refereegranskat)abstract
- The Alvarezsauridae represents a branch of peculiar basal coelurosaurs with an increasing representationof their Cretaceous radiation distributed worldwide. Here we describe a new member of the group, Bonapartenykus ultimus gen. et sp. nov. from Campanian-Maastrichtian strata of Northern Patagonia, Argentina. Bonapartenykus is represented by a single, incomplete postcranial skeleton. The morphologyof the known skeletal elements suggests close affinities with the previously described taxon from Patagonia, Patagonykus, and both conform to a new clade, here termed Patagonykinae nov. Two incomplete eggs have been discovered in association with the skeletal remains of Bonapartenykus, andseveral clusters of broken eggshells of the same identity were also found in a close proximity. These belong to the new ooparataxon Arriagadoolithus patagoniensis of the new oofamily Arriagadoolithidae, which provides first insights into unique shell microstructure and fungal contamination of eggs laid by alvarezsaurid theropods. The detailed study of the eggs sheds new light on the phylogenetic position of alvarezsaurids within the Theropoda, and the evolution of eggs among Coelurosauria. We suggest thatplesiomorphic alvarezsaurids survived in Patagonia until the latest Cretaceous, whereas these basal forms became extinct elsewhere.
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| 3. |
- Kundrát, Martin, 1969-, et al.
(författare)
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A putative upupiform bird from the Early Oligocene of the Central Western Carpathians and a review of fossil birds unearthed in Slovakia
- 2015
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Ingår i: Acta Zoologica. - Stockholm : Wiley-Blackwell. - 0001-7272 .- 1463-6395. ; 96:1, s. 45-59
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Tidskriftsartikel (refereegranskat)abstract
- An isolated hind limb of a miniature bird from an Early Oligocene locality (30–34 Ma) near Bystre (Slovakia) is described and analyzed. The tarsometatarsus (TMT) of the specimen is remarkably short relative to the tibiotarsus. When relative length ratios of the bones are compared with a sample of 29 extant and extinct birds with short metatarsi, the specimen variably clusters with some alcedinids, coraciids and trochilids. Log-clusters give less ambiguous results and indicate significant proximity of the Bystre specimen to the extinct messelirrisorids (Upupiformes) and the recent alcedinids (Coraciiformes). With regard to morphological details, such as those of the first metatarsal, II-IV metatarsal trochleae, intertrochlear incisurae and phalanges, the Slovak specimen shows a combination of features, which are distributed among recent upupiforms and coraciiforms as well as extinct upupiforms (Messelirrisor) and apodiforms (Eocypselus, Parargornis). Taken together, the metric and morphological data sets suggest that the specimen from Bystre is a coraciiform sensu lato rather than an apodiform bird. Within the Coraciiformes, the robust trochlea of MT-I with expanded dorsal shelf, the large medial and slit-like lateral intertrochlear incisura, and the long hindtoe suggest upupiform rather than alcedinid relationships.
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| 4. |
- Kundrát, Martin, 1969-, et al.
(författare)
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Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina
- 2020
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 30:21, s. 4263-4269.e2
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Tidskriftsartikel (refereegranskat)abstract
- The first dinosaur embryos found inside megaloolithid eggs from Auca Mahuevo, Patagonia, were assigned to sauropod dinosaurs that lived approximately 80 million years ago. Discovered some 25 years ago, these considerably flattened specimens still remain the only unquestionable embryonic remains of a sauropod dinosaur providing an initial glimpse into titanosaurian in ovo ontogeny. Here we describe an almost intact embryonic skull, which indicates the early development of stereoscopic vision, and an unusual monocerotic face for a sauropod. The new fossil also reveals a neurovascular sensory system in the premaxilla and a partly calcified braincase, which potentially refines estimates of its prenatal stage. The embryo was found in an egg with thicker eggshell and a partly different geochemical signature than those from the egg-bearing layers described in Auca Mahuevo. The cranial bones are comparably ossified as in previously described specimens but differ in facial anatomy and size. The new specimen reveals significant heterochrony in cranial ossifications when compared with non-sauropod sauropodomorph embryos, and demonstrates that the specialized craniofacial morphology preceded the postnatal transformation of the skull anatomy in adults of related titanosaurians.
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| 5. |
- Kundrát, Martin, 1969-, et al.
(författare)
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The first specimen of Archaeopteryx from the Upper Jurassic Mornsheim Formation of Germany
- 2019
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Ingår i: Historical Biology. - : TAYLOR & FRANCIS LTD. - 0891-2963 .- 1029-2381. ; 31:1, s. 3-63
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Tidskriftsartikel (refereegranskat)abstract
- From an initial isolated position as the oldest evolutionary prototype of a bird, Archaeopteryx has, as a result of recent fossil discoveries, become embedded in a rich phylogenetic context of both more and less crownward stem-group birds. This has prompted debate over whether Archaeopteryx is simply a convergently bird-like non-avialan theropod. Here we show, using the first synchrotron microtomographic examination of the genus, that the eighth or Daiting specimen of Archaeopteryx possesses a character suite that robustly constrains it as a basal avialan (primitive bird). The specimen, which comes from the Mornsheim Formation and is thus younger than the other specimens from the underlying Solnhofen Formation, is distinctive enough to merit designation as a new species, Archaeopteryx albersdoerferi sp. nov., but is recovered in close phylogenetic proximity to Archaeopteryx lithographica. Skeletal innovations of the Daiting specimen, such as fusion and pneumatization of the cranial bones, well vascularized pectoral girdle and wing elements, and a reinforced configuration of carpals and metacarpals, suggest that it may have had more characters seen in flying birds than the older Archaeopteryx lithographica. These innovations appear to be convergent on those of more crownward avialans, suggesting that Bavarian archaeopterygids independently acquired increasingly bird-like traits over time. Such mosaic evolution and iterative exploration of adaptive space may be typical for major functional transitions like the origin of flight.
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