I have not seen the full text so I don't know if there are new taxa named. My online checks did not find any.
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This page has links to 2-page image previews of each of the chapters. They have to be opened from this page to be viewed.
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This book summarizes the most relevant published paleontological information, supplemented by our own original work, on the record of Mesozoic mammalsâ evolution, their close ancestors and their immediate descendants. Mammals evolved in a systematically diverse world, amidst a dynamic geography that is at the root of the 6,500 species living today. Fossils of Mesozoic mammals, while rare and often incomplete, are key to understanding how mammals have evolved over more than 200 million years. Mesozoic mammals and their close relatives occur in a few Âdozen localities from Argentina, Brazil, Chile, ÂBolivia, and Peru spanning from the Mid- Triassic to the Late Cretaceous, with some lineages surviving the cataclysmic end of the Cretaceous period, into the Cenozoic of Argentina. There are roughly 25 recognized mammalian species distributed in several distinctive lineages, including australosphenidans, multituberculates, gondwanatherians, eutriconodonts, amphilestids and dryolestoids, among others. With its focus on diversity, systematics, phylogeny, and their impact on the evolution of mammals, there is no similar book currently available.
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Guillermo W. Rougier, AgustÃn G. Martinelli & AnalÃa M. Forasiepi (2021)
Introduction.
In: Mesozoic Mammals from South America and Their Forerunners: 1-24.
Springer Earth System Sciences. Springer, Cham.
doi:
https://doi.org/10.1007/978-3-030-63862-7_1https://link.springer.com/chapter/10.1007/978-3-030-63862-7_1Preview:
https://www.springer.com/gp/book/9783030638603Mammals from ancient times, living in past ecosystems surrounded by dinosaurs, toothed birds, fast running crocodyliforms, among other unfamiliar creatures, are a fascinating subject. These archaic mammals include the old, distant, relatives of the lineages that gave rise to the modern radiation of mammals and eventually ourselves. Mesozoic mammals are known from the Northern Hemisphere since the eighteenth century, while the first record of these creatures in the Southern Hemisphere came about half a century ago. As usual for Mesozoic mammals, the bulk of the SA species are solely known by jaw fragments and isolated teeth; but the collections also hold footprints, and a few beautifully preserved skulls and partial skeletons. In this chapter, we present a historical account of the first steps in the knowledge of SA Mesozoic mammals, the main personalities that helped to get it established as a distinct discipline, and provide definitions for some of the major mammalian groups.
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Guillermo W. Rougier, AgustÃn G. Martinelli & AnalÃa M. Forasiepi (2021)
The Origin and the Radiation of Early Mammals: A Southern Perspective.
In: Mesozoic Mammals from South America and Their Forerunners: 25-126
Springer Earth System Sciences. Springer, Cham.
doi:
https://doi.org/10.1007/978-3-030-63862-7_3https://link.springer.com/chapter/10.1007/978-3-030-63862-7_2Preview:
https://www.springer.com/gp/book/9783030638603The South American fossil record of Mesozoic mammals and close relatives is one of the best for Gondwana. Early mammals and relatives are found in about a dozen localities in Argentina, Brazil, Bolivia, Chile, and presumably Peru, including a broad sample of non-mammaliaform cynodonts of the Triassic age. Mesozoic mammals span from the latest Early Jurassic to the latest Cretaceous, furthermore some of those archaic lineages unexpectedly survived the end of the Cretaceous period, remaining as minority elements in the PaleoceneâMiocene faunal associations. The fossiliferous localities bearing these fossils are presented in this chapter, highlighting the geological setting, age, and their faunal associations.
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Non-mammaliaform cynodonts, formerly called "mammal-like reptiles," illustrate earlier states of the morphological architecture in the mammalian lineage. These mammalian forerunners show unique character combinations without direct counterparts among living vertebrates reflecting adaptations long lost along the millions of years of cynodont history. The fossil record from South America, originating mostly from the Middle to Late Triassic of Argentina and Brazil, is one of the most prolific worldwide. SA non-mammalian cynodonts are systematically diverse, including approximately 40 species that present great morphological disparity in skull shape, tooth morphology, pattern of tooth replacement, masticatory mechanisms, and locomotory architectures. In this chapter, we summarize the record of SA non-mammaliaform cynodonts.
As presently understood Australosphenida is a clade of Gondwanan taxa, including an array of Jurassic and Cretaceous extinct forms and the extant monotremes as the sole survivors. Mesozoic Australosphenida show plesiomorphic features in the lower jaw and derived tribosphenic, or tribosphenic-like, dentition, possibly acquired independently from boreal tribosphenic taxa, namely, therians and their immediate relatives. However, non-monotreme australosphenidans are known by rare and incomplete material making alternative hypotheses of dental homologies viable. Fossil and extant monotremes are hard to relate to Mesozoic non-monotreme australosphenidans, but a few dental and mandibular characters support them as members of the group. South American australosphenidans are the oldest currently known undisputed mammals, highlighting the early acquisition of complex tribosphenic dentitions and the importance of the fossil record from southern continents in the history of early mammals.
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"Triconodonts" is used here for mammaliaforms with three main cusps aligned along the mesiodistal axis of the postcanines, or forming a very broad (obtuse) triangle. This is not a natural group, but some of the smaller clades are, for example, Eutriconodonta and Amphilestheria. "Triconodonts" were abundant in Laurasian landmasses during the Jurassic and to a lesser degree during the Cretaceous. In contrast, the South American fossil record is scarce and the two known taxa come from a single locality in the EarlyâMiddle Jurassic of central Patagonia; even there they are rare members of the fauna and the materials rather poorly preserved. In this chapter, we summarize the known species from Argentina, which includes an amphilestherian and an eutriconodontan. Putative "triconodonts" from the Late Cretaceous of Argentina are regarded as premolars of meridiolestidans following recent re-interpretation (see Chap. Â6).
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Dryolestoids are iconic members of the Mesozoic mammalian associations in South America. They achieved a large taxonomic diversity in this region with disparate dental and cranial morphotypes ranging from the classical role of sharp-toothed insectivores to bunodont, complex dentitions reflecting omnivore/herbivore adaptations. The South American radiation of dryolestoids, the meridiolestidans, are among the most abundant Cretaceous mammals, surviving the K/Pg mass extinction and continuing until the Miocene as minor members of the South American biotas. New specimens have been recently discovered, some of them including associated upper and lower jaws, and exceptionally preserved skulls. These high-quality fossils provide crucial intraspecific dental variation, both along the tooth row and from upper to lower, allowing critical re-interpretation of some taxa originally named on the basis of isolated teeth or very incomplete material. The Cretaceous diversity of meridiolestidans has been grossly overestimated, with taxa based on different dental positions of what was later determinied to be a single taxon. One relatively poorly known Late Cretaceous taxon, Groebertherium, shares many features with the classical Holartic dryolestoids and may represent a Late Jurassic/Early Cretaceous foundational morphology expected for meridiolestidans.
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The cladothere Vincelestes neuquenianus, from the La Amarga Formation (Barremianâlower Aptian, Lower Cretaceous) of Patagonia, Argentina, is known by several nearly complete skulls, lower jaws, and abundant postcranial elements. This exceptional material is crucial in shaping our knowledge of early stem therians and high-level mammalian phylogeny. Vincelestes retains a relatively primitive braincase, similar to what is expected for the last common ancestor of all mammals, and a derived but unequivocally non-therian ear region and dentition.
The enigmatic Gondwanatheria includes mammals with a mosaic of plesiomorphic and apomorphic cranial and dental features challenging our attempts to reconstruct their phylogenetic affiliation. They are generally perceived as sharing a closer ancestor with multituberculates than with therians in a variably conceived Allotheria. Two major groups are classically recognized among the South American Gondwanatheria: the brachyodont-toothed Ferugliotheriidae and the hypsodont-toothed Sudamericidae, although not all taxa fall easily in these categories. The affinities of the Ferugliotheriidae are, however, unsettled, with some authors favoring the hypothesis that they are indeed a derived branch of multituberculates. The original foundational Patagonian finds of gondwanatherians have recently been much improved by spectacular Late Cretaceous Malagasy materials, which increase dental diversity of the group, provide detailed cranial/postcranial morphology, and support allotherian affinities for the group.
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The ichnogenus Ameghinichnus patagonicus described by Casamiquela in 1960, from the Middle Jurassic of Patagonia was the first evidence of a Mesozoic mammal in the continent. The trackways showed a sophisticated, ricochetal locomotion pattern, largely unsuspected at the time and with a surprisingly numerical abundant in the fossil site. Later on, other ichnotaxa were reported from the Middle Jurassic of Argentina and the Early Cretaceous of Brazil, complementing the earlier discoveries. We summarize in this chapter, the footprint records from Jurassic and Cretaceous rocks of South America, that have been putatively related to mammaliaforms, although these assignations can be uncertain to some degree, and perhaps related to non-mammaliaform cynodonts.
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Guillermo W. Rougier, AgustÃn G. Martinelli & AnalÃa M. Forasiepi (2021)
The South American Mesozoic Record and Early Evolution of Mammals.
In: Mesozoic Mammals from South America and Their Forerunners: 345-388
Springer Earth System Sciences. Springer, Cham
doi:
https://doi.org/10.1007/978-3-030-63862-7_10https://link.springer.com/chapter/10.1007/978-3-030-63862-7_10
The sparse record of archaic Mesozoic South American mammals extends from the latest Early Jurassic to the latest Cretaceous, involving about 115 Ma, which can be further extended to about 160 Ma, including the post-K/Pg evidence. We review here the distribution, predicted time of origin, and likely place of origin for the lineages covered in the preceding chapters during that span of time and against the evolving geological backdrop of continental drift and paleogeography. Size, dental diversity, and likely dietary specializations of the Mesozoic South American mammals are discussed in the context of Mesozoic mammals in general. A few of the many surprising advances in comparative genetic and molecular evolution are discussed as part of a holistic view of early mammalian evolution to which fossils can, and should, be integrated. Social, financial, and geographical issues affecting paleontological research in South America, early mammals, in particular, are highlighted. We recognize that we are still in the early stages of development and that much of what we know about Mesozoic South American mammals is likely to be drastically altered by finds in the continent or underrepresented areas from formery Gondwanan landmasses such as Antarctica or Africa. Their scarce mammalian fossil record has hampered their full incorporation into an integrated view of early mammalian evolution. The relatively robust paleontological community present in several South American countries, relatively inexpensive nature of the discipline, and extensive outcrops are likely to ensure continuity of a synergistic research agenda. The potential for novel data, regional strengths in systematics, and the global resurgent importance of time as integral to model-based phylogenies are auspicious signs for the future of Mesozoic mammal research in South America.
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