Browsing by Autor "Darin A. Croft"

Now showing 1 - 19 of 19

A new middle Miocene hegetotheriid (Notoungulata: Typotheria) and a phylogeny of the Hegetotheriidae
(Taylor & Francis, 2006) Darin A. Croft; Federico Anaya
ABSTRACT A new species of hegetotheriid notoungulate, Hemihegetotherium trilobus, is described from the middle Miocene (Laventan SALMA) Quebrada Honda Fauna of southern Bolivia. It differs from all previously described hegetotheriines in possessing a distinctly trilobed m3, a character state previously recorded only in pachyrukhine he-getotheriids. It further differs from other species of Hemihegetotherium in having a proportionately larger p2 and in overall size (being smaller than H. achataleptum and larger than H. torresi). A phylogenetic analysis of hegetotheriid genera coded for 26 characters supports referral of this species to Hemihegetotherium, but does not support the monophyly of Hegetotheriinae; the monophyly of Pachyrukhinae (including Prosotherium and Propachyrucos) is strongly supported. The resulting tree suggests that the lack of tibiofibular fusion in Oligocene pachyrukhines is a secondarily derived trait, but additional postcranial data are needed to provide a stronger test of this hypothesis. Hemihegetotherium trilobus is the most abundant ungulate at Quebrada Honda and is the only species of hegetotheriid present. This contrasts with most other South American paleofaunas in which pachyrukhines are more common than hegetotheriines (e.g., Arroyo Chasicó) and/or other small notoungulates are more common than hegetotheriids (e.g., Chucal, Nazareno). Although the absence of pachyrukhines at Quebrada Honda may be due to a lack of suitable habitat, it is also possible that pachyrukhines had not dispersed north to southern Bolivia by the middle Miocene. Further investigations of Quebrada Honda may help discriminate between these two alternatives and should also help clarify the biogeographic histories of other Miocene taxa.
A New Typothere Notoungulate (Mammalia: Interatheriidae), from the Miocene Nazareno Formation of Southern Bolivia
(Asociación Paleontológica Argentina, 2020) Darin A. Croft; Federico Anaya
We describe a new interatheriid notoungulate, Juchuysillu arenalesensis gen. et sp. nov., based on six partial upper and lower dentitions from the early to middle Miocene Nazareno Formation of southern Bolivia. A specimen is also referred to J. arenalesensis from the early middle Miocene (Langhian) locality of Cerdas, Bolivia (ca. 100 km to the northwest). The new species is distinguished by its very small size (ca. 15% smaller than Protypotherium minutum) and the unique combination of shallow ectoloph sulci on P3-4, length of M1 > M2 > M3, trapezoidal upper molars, and absence of a buccal talonid sulcus on m3. A second, larger interatheriid species is present at Nazareno but is not represented by remains sufficiently complete for a more precise identification. A phylogenetic analysis indicates that J. arenalesensis represents a unique lineage within Interatheriinae that diverged after Protypotherium sinclairi but before Miocochilius anomopodus, Caenophilus tripartitus, Miocochilius federicoi, and several species of Protypotherium, including Protypotherium australe. Juchuysillu arenalesensis is one of two small (< ca. 3 kg) typotheres at Nazareno; its body mass is estimated at 1.1 kg. An updated faunal list for the Nazareno Formation includes 19 species of mammals pertaining to seven orders and 15 families; fragmentary turtle (Testudinidae?) and bird (Phorusrhacidae) remains are also present. The precise age of Nazareno Formation vertebrates is unknown, but the presence of at least three notoungulate species shared with Cerdas suggests a similar (∼16–15 Ma) age for the fossil-bearing levels.
Analysis of function in the absence of extant functional homologues: a case study using mesotheriid notoungulates (Mammalia)
(Cambridge University Press, 2007) Bruce J. Shockey; Darin A. Croft; Federico Anaya
We use two approaches to test hypotheses regarding function in a group of extinct mammals (Family Mesotheriidae, Order Notoungulata) that lack any close extant relatives: a principle-derived paradigm method and empirically derived analog method. Metric and discrete morphological traits of mesotheriid postcranial elements are found to be consistent with the morphology predicted by a modified version of Hildebrand's paradigm for scratch diggers. Ratios of in-force to out-force lever arms based on skeletal elements indicate that the mesotheriids examined had limbs modified for high out-forces (i.e., they were “low geared”), consistent with the digging hypothesis. Other mesotheriid characters, such as cleft ungual phalanges, a curved olecranon, and a highly modified pelvis (with extra vertebrae incorporated into the sacrum and fusion between the ischium and the axial skeleton) are regarded as being functionally significant for digging and also occur in a variety of extant diggers. Analog methods indicate that mesotheriids share numerous traits common to a variety of extant diggers. Principal component analyses of postcranial elements indicate that mesotheriids consistently share morphometric space with larger extant fossorial mammals: aardvark, anteaters, wombats, and badger. Likewise, discriminant function analyses categorized mesotheriids as fossorial, though imperfectly analogous to the extant diggers analyzed. Thus, both theory-driven and empirically derived methods of estimating function in these extinct taxa support a digging hypothesis for the mesotheriids examined. Adaptations for digging in both the forelimb and sacropelvic functional complexes of mesotheriids provide independent support for the fossorial hypothesis.
Australogale leptognathus, gen. et sp. nov., a Second Species of Small Sparassodont (Mammalia: Metatheria) from the Middle Miocene Locality of Quebrada Honda, Bolivia
(Springer Science+Business Media, 2018) Russell K. Engelman; Federico Anaya; Darin A. Croft
Chronology of Miocene terrestrial deposits and fossil vertebrates from Quebrada Honda (Bolivia)
(Elsevier BV, 2020) Luís Gibert; Alan L. Deino; Luís Valero; Federico Anaya; María Lería; Beverly Z. Saylor; Darin A. Croft
Giant fossil tortoise and freshwater chelid turtle remains from the middle Miocene, Quebrada Honda, Bolivia: Evidence for lower paleoelevations for the southern Altiplano
(Elsevier BV, 2015) Edwin‐Alberto Cadena; Federico Anaya; Darin A. Croft
Lithostratigraphy, chronostratigraphy, and sedimentary environments of the middle Miocene Quebrada Honda Basin in southern Bolivia and implications for Andean climate and uplift
(Elsevier BV, 2022) Beverly Z. Saylor; Angeline M. Catena; Daniel I. Hembree; Federico Anaya; Darin A. Croft
New Chinchillid Rodents (Hystricognathi: Caviomorpha) from Northern Chile and Bolivia Fill a 17-Million-Year Gap in the Pan-Chinchilline Fossil Record
(Springer Science+Business Media, 2021) Darin A. Croft; John J. Flynn; André R. Wyss; Reynaldo Charrier; Federico Anaya
New Data on Miocene Neotropical Provinciality from Cerdas, Bolivia
(Springer Science+Business Media, 2009) Darin A. Croft; Federico Anaya; David Auerbach; Carmala N. Garzione; Bruce J. MacFadden
New mammal faunal data from Cerdas, Bolivia, a middle-latitude Neotropical site that chronicles the end of the Middle Miocene Climatic Optimum in South America
(Taylor & Francis, 2016) Darin A. Croft; Alfredo A. Carlini; Martín R. Ciancio; Diego Brandoni; Nicholas E. Drew; Russell K. Engelman; Federico Anaya
We provide new and revised identifications of mammals from the early middle Miocene (Langhian age, Colloncuran South American Land Mammal Age [SALMA]) of Cerdas, Bolivia. We also formally name a new typothere notoungulate, Hegetotherium cerdasensis, sp. nov., that can be distinguished by the absence of an external talonid sulcus on m3 and its small size (15–25% smaller than Hegetotherium mirabile). We refer several typothere specimens from Nazareno, Bolivia, to H. cerdasensis, which suggests that the two sites are of similar age. We report the first sparassodont and astrapothere remains from Cerdas. Sparassodont remains include an associated basicranium and mostly complete mandible; the species appears to represent a new, small-bodied borhyaenoid. Astrapothere remains consist of many tooth fragments from a new species of the subfamily Uruguaytheriinae. A partial sloth dentary from Cerdas likely pertains to the subfamily Megatheriinae and is the first report of the family Megatheriidae from the site. A newly discovered peltephilid armadillo specimen includes a partial articulated carapace that supports recognition of the Cerdas taxon as a new species. The two dasypodids of Cerdas (one Euphractini, one Eutatini) represent two new species closely related to undescribed species from the late middle Miocene (Serravallian age, Laventan SALMA) of Quebrada Honda, Bolivia. The mammals of Cerdas indicate that (1) the middle latitudes (southern tropics) contributed significantly to the diversity of Miocene mammal communities in South America; and (2) the Middle Miocene Climatic Optimum was a key factor in the differentiation of South American mammal assemblages.Citation for this article: Croft, D. A., A. A. Carlini, M. R. Ciancio, D. Brandoni, N. E. Drew, R. K. Engelman, and F. Anaya. 2016. New mammal faunal data from Cerdas, Bolivia, a middle-latitude Neotropical site that chronicles the end of the Middle Miocene Climatic Optimum in South America. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1163574.
New Middle Miocene Caviomorph Rodents from Quebrada Honda, Bolivia
(Springer Science+Business Media, 2011) Darin A. Croft; Jennifer Chick; Federico Anaya
New palaeothentid marsupials (Paucituberculata) from the middle Miocene of Quebrada Honda, Bolivia, and their implications for the palaeoecology, decline and extinction of the Palaeothentoidea
(Taylor & Francis, 2016) Russell K. Engelman; Federico Anaya; Darin A. Croft
Paucituberculatan marsupials, particularly members of the family Palaeothentidae, were important components of South American mammal communities during much of the Cenozoic. However, after the late early Miocene, palaeothentid remains are rare in the fossil record, and the group is last recorded at late middle Miocene sites in Colombia, Bolivia and possibly Argentina. Here, we describe new specimens of palaeothentids from one of these late middle Miocene sites, Quebrada Honda, Bolivia, which include: (1) the first described lower dentitions of Acdestis maddeni, which exhibit distinctive features such as a greatly elongated paracristid and a single-rooted m4; (2) the first described late middle Miocene palaeothentines, representing two new species of Palaeothentes, P. serratus sp. nov. and P. relictus sp. nov., distinguished from other species of Palaeothentes by the presence of an anterobasal cingulid and reduced anterior trigonid crest, among other features; and (3) remains of a third new species, Chimeralestes ambiguus gen. et sp. nov., distinguished from other palaeothentids by its combination of a labially positioned cristid obliqua, reduced m4, and sharply curved entocristid. Phylogenetic and palaeoecological analyses show that Quebrada Honda palaeothentids were taxonomically and morphologically diverse and likely spanned a wide range of ecological niches. Combined with the wide geographical distribution of palaeothentoids during the late middle Miocene, this suggests that the disappearance of these marsupials was preceded by an abrupt rather than gradual decline in taxonomic and ecological diversity as well as geographical range.http://zoobank.org/urn:lsid:zoobank.org:pub:DA7E10BA-7203-4F5A-A3AB-F0E7352B101C
New Proterotheriids from the Middle Miocene of Quebrada Honda, Bolivia, and Body Size and Diversity Trends in Proterotheriid and Macraucheniid Litopterns (Mammalia)
(Asociación Paleontológica Argentina, 2020) Andrew J. McGrath; Federico Anaya; Darin A. Croft
In this work, we describe two new species of proterotheriid litopterns, Olisanophus riorosarioensis gen. et sp. nov. and Olisanophus akilachuta sp. nov. from the middle Miocene (Laventan SALMA) of Quebrada Honda, Bolivia. When incorporated into a recently published phylogenetic analysis (40 taxa; 92 characters), they plot as sister taxa, partially supported by their connected metaconule and protocone on M3. Additionally, we revise the taxonomy of two contemporaneous proterotheriids from La Venta, Colombia. ‘Prolicaphrium' sanalfonensis is reassigned to Mesolicaphrium gen. nov., with a prominent protocone on M3 as an autapomorphy of the genus. We revalidate the genus Neodolodus for Neodolodus colombianus, a species referred to ‘Prothoatherium' or Lambdaconus by previous authors. We used the paleotree R package to examine evolutionary trends in diversity and body size (using m1 length as a proxy) in proterotheriid and macraucheniid litopterns in a phylogenetic context. Proterotheriids were more diverse in the Paleogene than their fossil record indicates; their diversity peaked in the early Miocene and gradually declined until the Pleistocene. Macraucheniids experienced two peaks in diversity, in the early and late Miocene, but were still fairly diverse in the Pleistocene, unlike proterotheriids. Multiple proterotheriid lineages became larger during the Paleogene, but body size was roughly static during the Neogene, with no obvious link between phylogeny and size. Macraucheniids can be grouped into three size classes that are phylogenetically conserved and roughly correspond temporally to Eocene (small Polymorphis spp.), Miocene–Pliocene (medium-sized ‘cramaucheniines’ and early macraucheniines, e.g., Theosodon, Promacrauchenia), and Pleistocene (large macraucheniines, e.g., Macrauchenia) species.
New Remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; Chronological and Biogeographical Implications
(Springer Science+Business Media, 2017) Diego Brandoni; Alfredo A. Carlini; Federico Anaya; Phil Gans; Darin A. Croft
New Specimens of Acyon myctoderos (Metatheria, Sparassodonta) from Quebrada Honda, Bolivia
(Asociación Paleontológica Argentina, 2014) Russell K. Engelman; Federico Anaya; Darin A. Croft
Despite being the dominant group of South American mammalian carnivores for much of the Neogene, most post-early Miocene sparassodonts (Metatheria) are poorly known. Here, we describe new specimens of the hathliacynid sparassodont Acyon myctoderos Forasiepi et al. from the middle Miocene locality of Quebrada Honda, Bolivia, including a juvenile specimen that preserves the first known hathliacynid DP3. This specimen is unique among sparassodonts in preserving both upper and lower deciduous premolars and suggests that hathliacynids may have differed from borhyaenoid sparassodonts in having simultaneous eruption of M3 and m4 rather than M4/m4. Another specimen from Quebrada Honda tentatively assigned to A. myctoderos preserves the first known long bones (femur, tibia) of this genus, allowing us to estimate its body mass (13–17.5 kg) based on postcranial data. These new specimens document further morphological and ontogenetic variation within A. myctoderos as well as the Sparassodonta as a whole.
Paleoenvironmental analysis of the Neotropical fossil mammal site of Cerdas, Bolivia (middle Miocene) based on ichnofossils and paleopedology
(Elsevier BV, 2016) Angeline M. Catena; Daniel I. Hembree; Beverly Z. Saylor; Federico Anaya; Darin A. Croft
Paleosol and ichnofossil evidence for significant Neotropical habitat variation during the late middle Miocene (Serravallian)
(Elsevier BV, 2017) Angeline M. Catena; Daniel I. Hembree; Beverly Z. Saylor; Federico Anaya; Darin A. Croft
The flora, fauna, and paleoenvironment of the late Middle Miocene Quebrada Honda Basin, Bolivia (Eastern Cordillera, Central Andes)
(Elsevier BV, 2024) Caroline A. E. Strömberg; Beverly Z. Saylor; Russell K. Engelman; Angeline M. Catena; Daniel I. Hembree; Federico Anaya; Darin A. Croft
Miocene ecosystem change in the Central Andes is not well understood because of a dearth of well-dated fossil sites from the region. The late Middle Miocene (∼13–12 Ma) Quebrada Honda Basin (QHB) in southern Bolivia (22° S) helps fill this gap and provide vital insights into Neotropical paleoenvironments . The site is among the best-characterized Middle Miocene terrestrial vertebrate sites of South America and has a robust temporal, spatial, and lithostratigraphic framework for analyzing its sedimentary facies, fossils, and paleoenvironment. Here, we present new plant silica (phytolith) assemblage data from the QHB as well as new analyses of QHB faunal data. Phytolith assemblage data indicate two broad vegetation types : one suggestive of more open habitats (≥ 60% presumably open-habitat grasses) and the other of more closed habitats (typically dominated by potential bamboos and other forest indicators). Compositional overlap suggests that these vegetation types represent distinct plant communities within a broader biome that lacks an exact modern analog among studied Neotropical vegetation; however, it was likely akin to modern Neotropical semi-deciduous/dry forest to wooded savanna. No clear temporal or spatial trends in phytolith composition are evident in the QHB, and the same is broadly true for QHB vertebrates based on analyses of 872 identified specimens. Abundances of some mammals (certain rodents, armadillos, turtles, and the notoungulate Hemihegetotherium ) vary slightly among well-sampled local areas and stratigraphic intervals, paralleling phytolith assemblage data suggesting local heterogeneity. The new floral and faunal data, combined with previous studies of paleosols , ichnofossils , ectothermic vertebrates, and mammal ecological diversity of the QHB, point to a mosaic landscape in lowland subtropical to tropical conditions that did not change substantially during the preserved interval. These results add critically to our understanding of Neotropical landscape evolution , suggesting that the QHB had not undergone substantial uplift, counter to recent reconstructions of Andean orogeny in the Eastern Cordillera. • The Middle Miocene Quebrada Honda Basin (QHB) preserves vital fossil data from the Neotropics. • We integrate new reconstructions of QHB plant and animal communities. • Vegetation was heterogeneous, spanning dry forest to wooded savanna. • The diverse mammal fauna varied little through time or across the basin. • The Central Andes were still at relatively low elevation 12 million years ago. Velizar Simeonovski made the reconstruction of H. trilobus
Two new macraucheniids (Mammalia: Litopterna) from the late middle Miocene (Laventan South American Land Mammal Age) of Quebrada Honda, Bolivia
(Taylor & Francis, 2018) Andrew J. McGrath; Federico Anaya; Darin A. Croft
We describe two new macraucheniid litopterns from the late middle Miocene (ca. 13 Ma) Quebrada Honda Fauna of southern Bolivia. The holotype of ‘Theosodon’ arozquetai, sp. nov., is a partial cranium preserving RI2–M3 and LP1–M3, elements of the hind limb, and two metapodials. An upper cheek tooth series is also referred to this species. The holotype of Llullataruca shockeyi, gen. et sp. nov., is a mandible preserving nearly the entire lower dentition. A dentary, several upper teeth, and a variety of postcranial elements are also referred to this species. Two specimens from the slightly older locality of Cerdas, Bolivia, are assigned to L. cf. shockeyi. A phylogenetic analysis recovers ‘T.’ arozquetai as sister to Theosodon spp., and we provisionally refer it to that genus pending its revision. Llullataruca shockeyi forms a polytomy with three late Oligocene–early Miocene ‘cramaucheniines’ and the later-diverging macraucheniids. The body mass of ‘T.’ arozquetai is estimated at 80.8–116.2 kg, slightly smaller than early Miocene T. garretorum. Llullataruca shockeyi is among the smallest known macraucheniids based on dental dimensions and is estimated at 35.3–54.6 kg. Theosodon' arozquetai and L. shockeyi are the first well-characterized macraucheniids from the middle Miocene, and the latter species demonstrates that relatively early-diverging lineages persisted at least 7 million years longer in tropical latitudes than they did in Patagonia. http://zoobank.org/urn:lsid:zoobank.org:pub:D26BB67B-D8E1-4D36-9552-4391874CF69C SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: McGrath, A. J., F. Anaya, and D. A. Croft. 2018. Two new macraucheniids (Mammalia: Litopterna) from the late middle Miocene (Laventan South American Land Mammal Age) of Quebrada Honda, Bolivia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1461632.