Browsing by Author "Giannini, Norberto P."
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Item The chiropteran premaxilla : a reanalysis of morphological variation and its phylogenetic interpretation ; American Museum novitates, no. 3585(New York, NY : American Museum of Natural History, 2007) Giannini, Norberto P.; Simmons, Nancy B.The mammalian premaxilla, which bears the incisor teeth, is composed of a body and two processes (nasal and palatine) that articulate with other rostral bones via four cranial sutures. In bats, the premaxilla is modified in many ways, and this variation has been extensively used in bat systematics. The premaxilla has provided characters to diagnose a number of important taxonomic groupings--most notably, the division of Microchiroptera into the infraorders Yinochiroptera and Yangochiroptera. Recent molecular studies have challenged the monophyly of Microchiroptera, and several families have been transferred to clades other than those in which they were placed traditionally. Because premaxillary characters have figured prominently among those used to establish the traditional classification of bats, we compared the anatomy of the bone across suprageneric bat groups and provide revised descriptions of its variation. On the basis of extensive material examined, we generated 16 new characters, of which at least 12 are partially applicable to all Chiroptera, and several of which are informative within specific bat groups. Three new characters code variation in the basic structure of the chiropteran premaxilla in a new way. As a result, the traditional character defining Yinochiroptera (a "movable premaxilla") was found to lack an anatomical basis; by contrast, Yangochiroptera was still supported. Still, a tree search using just the new premaxillary characters recovered Yinochiroptera as monophyletic. Even with a low character-to-taxon ratio, premaxillary characters recover a number of clades recognized in recent phylogenetic studies of bats. Mapping of characters onto the latest molecular and morphological chiropteran trees required many more extra steps in the former than in the latter. Our interpretation of premaxillary variation in bats suggests two opposing trends in different lineages: one toward weakening and eventual loss of the bone, and the other toward a strengthening via suture fusion. We conclude that, despite some homoplasy, the chiropteran premaxilla is richer in potentially phylogenetically informative characters than previously thought and that it should be explored further in systematic studies of bats at a variety of systematic levels.Item Comparative postnatal ontogeny of the skull in Dromiciops gliroides (Marsupialia, Microbiotheriidae). American Museum novitates ; no. 3460(New York, NY : American Museum of Natural History, 2004) Giannini, Norberto P.; Abdala, Fernando.; Flores, David A.Dromiciops gliroides is the single extant representative of the marsupial family Microbiotheriidae. The importance of D. gliroides stems from its peculiar cranial anatomy (specifically the configuration of the tympanic region) and dentition and from its controversial position in the phylogenetic tree of marsupials--a South American form more closely related to Australasian marsupials. We studied the postnatal ontogeny of the skull in D. gliroides by analyzing qualitative and allometric aspects of the development of cranial structures. We compared recently weaned young individuals with adults and described the bivariate and multivariate allometric trends of 14 cranial dimensions for a sample of 37-51 specimens. Most cranial components develop in a way similar to didelphids studied so far. However, some trends (e.g., growth of the orbit) seem particular to D. gliroides. The microbiotheriid bulla of D. gliroides, a structure to which five basicranial bones contribute parts, is already present in its highly derived condition in the youngest specimens of our series. We conclude that except for the bulla, most of the cranial development in D. gliroides is highly conservative and that some peculiarities may be shared with other marsupials of similarly small body size. Data on australidelphians and small-size didelphids are needed to contrast these patterns.Item Element homology and the evolution of dental formulae in megachiropteran bats (Mammalia, Chiroptera, Pteropodidae) ; American Museum novitates, no. 3559(New York, NY : American Museum of Natural History, 2007) Giannini, Norberto P.; Simmons, Nancy B.Variation in dental formulae observed in megachiropteran bats poses element homology problems. Identity of individual teeth has been controversial, with authors differing in their assessment of individual tooth homology, particularly with respect to incisors and premolars, in several taxa. Also, newly described taxa exhibit dental formulae whose implications for tooth homology have been little discussed. We compared crown morphology, tooth replacement, and dental anomalies in representatives of all megachiropteran genera. Our observations confirm the generalized megachiropteran dental formula (34 teeth represented by I1, I2, C, P1, P3, P4, M1, M2, i1, i2, c, p1, p3, p4, m1, m2, and m3) and establishes the homology of each tooth in most megachiropteran taxa in which reduction in tooth number has taken place. Some of our conclusions confirm presumed homologies postulated by previous authors, but in other cases new homology assignments are proposed. Uncorroborated assignments are reduced to just two taxa, Harpyionycteris and Nyctimeninae, both of which remain problematic with respect to homologies of the incisor dentition. Mapping tooth presence/absence on previously published phylogenetic trees reveals modest levels of ambiguity and homoplasy in patterns of tooth reduction in Pteropodidae, and indicates that reversals involving the reappearance of an ancestrally lost tooth may have taken place. Our results are consistent with dental field theory, which explains both reversals and anomalies as a regulatory variation that does not affect element homology because the latter is supported by structural genes.Item Morphology and evolution of sesamoid elements in bats (Mammalia, Chiroptera). (American Museum novitates, no. 3905)(American Museum of Natural History., 2018-08-17) Amador, Lucila Inés.; Giannini, Norberto P.; Simmons, Nancy B.; Abdala, Virginia.Sesamoids are skeletal elements found within a tendon or ligament as it passes around a joint or bony prominence. Here we review the distribution of sesamoids in bats, the only mammals capable of powered flight. Our survey included bat species representing most extant families as well as two key Eocene fossil bats in which sesamoids are exquisitely preserved, Onychonycteris finneyi and Icaronycteris index. We identified 46 separate sesamoid elements (or sets of elements) from dissections of selected bat taxa, with no more than 23 of these present in any given species. Among the sesamoids identified in our survey, 12 have not previously been described in bats. We also identified seven sesamoids previously described in the literature that are not present in our sample of species. No sesamoids were found to be exclusive to the fossil taxa in our study; all the sesamoids observed in Onychonycteris and Icaronycteris have apparent homologs among extant species. We mapped the presence/absence of the 46 sesamoids onto a bat phylogeny. Based on these optimizations, we discuss homology issues and evolutionary history of some of the most taxonomically widespread sesamoids. Functional inferences regarding some sesamoids can be made based on what is known about bat musculoskeletal morphology, although further biomechanical studies are required to test the hypotheses proposed here. Sesamoids will continue to be a source of interesting insights about the evolution of bats and their unique locomotor abilities.Item A new species of Histiotus Gervais, 1856 (Chiroptera, Vespertilionidae), from the Pacific Coast of Northern Peru (American Museum novitates, no. 3979)(American Museum of Natural History., 2021-10-13) Velazco, Paúl M.; Almeida, Francisca Cunha; Cláudio, Vinícius C.; Giménez, Analía L.; Giannini, Norberto P.The Pacific coastal desert of Peru harbors a unique bat fauna, including narrowly endemic taxa adapted to arid environments. This region was also the setting where several pre-Incan civilizations flourished. The Moche culture (100–850 CE) was one of those, with a rich and diverse material culture that included strikingly realistic ceramic representations of the regional flora and fauna. In particular, one Mochica pottery vessel is in the form of a bat that, based on external characteristics (large pinnae and tragus, pinnae connected by high band of membrane across the forehead, and lack of noseleaf), clearly represents an individual of the vespertilionid genus Histiotus. The morphological characteristics observed in this vessel, in addition to the area of influence of the Moche culture, suggests that this vessel depicts a species previously unknown to science that we describe here as new on the basis of two specimens obtained in 2012 in the Peruvian department of Piura. Our new species, Histiotus mochica, can be distinguished from other congeners by having unicolored dorsal fur, medial lobes of pinnae greater than 9.5 mm wide, and a well-developed (>4.3 mm high) transverse band of skin connecting the pinnae. Cytochrome b sequence data indicate that the new species is sister to H. humboldti from the Andes of Colombia and northern Ecuador. The new species is a medium-sized Histiotus that clusters with H. laephotis, H. velatus, and with small specimens of H. montanus in our multivariate analyses. With the description of H. mochica, the diversity of the genus increases to 11 species. We provide a key based on external characters of all known species of Histiotus.Item On the cranial osteology of Chiroptera. 1, Pteropus (Megachiroptera, Pteropodidae). Bulletin of the AMNH ; no. 295(New York, NY : American Museum of Natural History, 2006) Giannini, Norberto P.; Wible, John R.; Simmons, Nancy B.Although detailed anatomical descriptions of skull morphology are available for representatives of many mammalian orders, no such descriptive work exists for bats, a group that comprises over 20% of extant mammalian species. In this paper, we provide a detailed description of the skull of Pteropus (Mammalia: Chiroptera: Megachiroptera: Pteropodidae) and establish a system of cranial nomenclature following the Nomina Anatomica Veterinaria. Based on a series of specimens of Pteropus lylei, we describe the skull as a whole and the morphology of external surfaces of 24 bones (7 rostral, 16 cranial, plus the mandible) and 17 teeth. We describe internal surfaces and additional bones of disarticulated skulls of Pteropus livingstonii and use material from the same species to describe the middle ear ossicles and the petrosal bone. We include a description of the hyoid apparatus and larynx based on Pteropus tonganus and a description of the deciduous dentition based on Pteropus hypomelanus. Using a sectioned fetus, we determine the content and homology of all cranial foramina present in the skull of Pteropus. We outline the ontogenetic changes from newborn pups to adults, considering changes in skull shape and the sequence of bone fusion and tooth eruption. Based on selected comparisons to other megabats, we discuss broad patterns of variation in general cranial shape, and interspecific variation in sutures, foramina, processes, and dentition. Overall, this work establishes a descriptive and nomenclatorial benchmark for chiropteran skull anatomy in line with similar works in other mammalian orders, with the aim of creating common ground for comparative, phylogenetic, and functional studies of the bat skull, including comparisons with other mammals.Item Phylogenetic relationships of the enigmatic harpy fruit bat, Harpyionycteris (Mammalia, Chiroptera, Pteropodidae) ; American Museum novitates, no. 3533(New York, NY : American Museum of Natural History, 2006) Giannini, Norberto P.; Almeida, Francisca Cunha.; Simmons, Nancy B.; DeSalle, Rob.Harpy fruit bats, two closely related species in the genus Harpyionycteris (Chiroptera: Pteropodidae), exhibit a suite of unique craniodental traits. For this reason, the affinities of these bats have remained unclear, and most systematists have placed them in a group of their own (Harpyionycterinae Miller, 1907). The multicuspidate pattern of the cheek teeth in Harpyionycteris has generated speculation that it may represent an ancestral tribosphenic pattern lost in other pteropodids. In this contribution we propose a phylogenetic placement of Harpyionycteris based on parsimony analysis of complete sequences from two coding genes, the nuclear vWF (exon 28) and the mitochondrial cytochrome b (cyt-b). Both datasets, independently and in combination, strongly support a close relationship between Harpyionycteris and Dobsonia, as originally proposed by Andersen (1912, Catalogue of Chiroptera, British Museum Trustees). In turn, this group nests deeply inside Pteropodidae but it is not closely related to any particular suprageneric clade. Based on other data, we postulate that Aproteles also belongs in this group and therefore propose the expansion of Harpyionycterinae to include Harpyionycteris, Aproteles, and Dobsonia. Regarding the dentition, our results strongly reject the tribosphenic hypothesis advanced by some authors. The multicuspidate cheek tooth pattern seen in Harpyionycteris appears uniquely derived and related to specialized feeding habits and it thus has no direct bearing on the evolution of the typical pteropodid dentition from the tribosphenic pattern of microchiropterans and other mammals.Item Redescription and phylogenetic position of the early Miocene penguin Paraptenodytes antarcticus from Patagonia ; American Museum novitates, no. 3525(New York, NY : American Museum of Natural History, 2006) Bertelli, Sara, Ph. D.; Giannini, Norberto P.; Ksepka, Daniel T.Paraptenodytes antarcticus is one of the best-known and most complete fossil penguins. This taxon is so distinctive that it has traditionally been classified in its own subfamily (Sphenisciformes: Paraptenodytinae) separate from all living penguins (Spheniscinae). The well-preserved partial skull of P. antarcticus is one of our richest sources of data on early penguin cranial morphology. We provide an updated description of the skull of P. antarcticus in a comparative context and use this information to explore the phylogenetic relationships of this taxon. Three cladistic analyses using an osteology dataset, a larger morphological dataset (including osteological, soft tissue, behavior, and oological characters) and a combined (morphological + molecular) dataset all recover Paraptenodytes as the sister taxon to a clade including all extant penguins. The placement of Paraptenodytes outside the crown clade of extant penguins reveals the order in which many spheniscid synapomorphies were acquired and lends support to the hypothesis that modern penguins had Subantarctic ancestors.Item A species-level phylogeny of Old World fruit bats with a new higher-level classification of the Family Pteropodidae. (American Museum novitates, no. 3950)(American Museum of Natural History., 2020-04-13) Almeida, Francisca Cunha.; Simmons, Nancy B.; Giannini, Norberto P.;Old World fruit bats (Chiroptera: Yinpterochiroptera: Pteropodidae) are a diverse radiation endemic to the tropics of Africa, Asia, Australia, and nearby island archipelagos. Recent molecular analyses have provided considerable resolution of phylogenetic relationships within this group, but many points of uncertainty have remained including the position of several enigmatic taxa (e.g., Notopteris, Eidolon), relationships among species in more diverse subfamilies and genera (e.g., Pteropodinae, Pteropus, Epomophorus), and topology of the backbone of the tree. Here we provide a new, synthetic analysis including representatives of all 45 currently recognized genera and enhanced sampling in several speciose genera. Our matrix included four nuclear genes regions (vWF, RAG1, RAG2, and BRCA1) and four mitochondrial gene loci (Cytb, tRNA valine, 12S rRNA, and 16S rRNA) for a total of >8000 bp including new sequence data for 13 species. Maximum likelihood and Bayesian analyses resulted in trees supporting recognition of six main suprageneric clades similar in content to those identified in our previous studies. We did not recover strong support for relationships among the main clades along the backbone of the tree, but identified many well-supported clades within all of the major groups. Based on these results, we propose a new classification for Pteropodidae comprising eight subfamilies and 14 tribes, and including several new and/or replacement higher-level taxonomic names for which we provide morphological diagnoses.Item Supplemental Material for 'A species-level phylogeny of Old World fruit bats with a new higher-level classification of the Family Pteropodidae. (American Museum novitates, no. 3950)'(American Museum of Natural History., 2020-04-13) Almeida, Francisca Cunha.; Simmons, Nancy B.; Giannini, Norberto P.Supplemental Material for 'A species-level phylogeny of Old World fruit bats with a new higher-level classification of the Family Pteropodidae. (American Museum novitates, no. 3950)'Item Systematic mammalogy : contributions in honor of Guy G. Musser. (Bulletin of the American Museum of Natural History, no. 331)(New York : American Museum of Natural History., 2009) Voss, Robert S.; Carleton, Michael D.; Anderson, Robert P.; Gutiérrez, Eliécer E.; Arroyo-Cabrales, Joaquín.; Flynn, Lawrence J. (Lawrence John), 1932-; Gardner, Alfred L.; Giannini, Norberto P.; Almeida, Francisca Cunha.; Simmons, Nancy B.; Heaney, Lawrence R.; Balete, Danilo S., 1960-; Rickart, Eric A.; Veluz, M. Josefa.; Jansa, Sharon A.; Helgen, K. M. (Kristofer M.); Helgen, Lauren E.; Holden, Mary Ellen.; Levine, Rebecca S.; Jenkins, Paulina D.; Lunde, Darrin P.; Moncrieff, Clive B.; Myers, Philip, 1947-; Catzeflis, François.; Carmignotto, Ana Paula.; Barreiro Rodríguez, Josefina.; Wahlert, John H.; Musser, Guy G.Contents: They sort out like nuts and bolts : a scientific biography of Guy G. Musser / Michael D. Carleton -- Taxonomy, distribution, and natural history of the genus Heteromys (Rodentia: Heteromyidae) in central and eastern Venezuela, with the description of a new species from the Cordillera de la Costa / Robert P. Anderson and Eliécer E. Gutiérrez -- Review of the Oryzomys couesi complex (Rodentia: Cricetidae: Sigmodontinae) in western Mexico / Michael D. Carleton and Joaquin Arroyo-Cabrales -- The antiquity of Rhizomys and independent acquisition of fossorial traits in subterranean muroids / Lawrence J. Flynn -- A new species of Reithrodontomys, subgenus Aporodon (Cricetidae: Neotominae), from the highlands of Costa Rica, with comments on Costa Rican and Panamanian Reithrodontomys / Alfred L. Gardner and Michael D. Carleton -- Phylogenetic relationships of harpyionycterine megabats (Chiroptera: Pteropodidae) / Norberto P. Giannini, Francisca Cunha Almeida, and Nancy B. Simmons -- A new genus and species of small "tree-mouse" (Rodentia, Muridae) related to the Philippine giant cloud rats / Lawrence R. Heaney, Danilo S. Balete, Eric A. Rickart, M. Josefa Veluz, and Sharon A. Jansa -- Biodiversity and biogeography of the moss-mice of New Guinea : a taxonomic revision of Pseudohydromys (Muridae: Murinae) / Kristofer M. Helgen and Lauren E. Helgen -- Systematic revision of sub-Saharan African dormice (Rodentia: Gliridae). Part 2, Description of a new species of Graphiurus from the central Congo Basin, including morphological and ecological niche comparisons with G. crassicaudatus and G. lorraineus / Mary Ellen Holden and Rebecca S. Levine -- Descriptions of new species of Crocidura (Soricomorpha: Soricidae) from mainland Southeast Asia, with synopses of previously described species and remarks on biogeography / Paulina D. Jenkins, Darrin P. Lunde, and Clive B. Moncrieff -- The six opossums of Félix de Azara : identification, taxonomic history, neotype designations, and nomenclatural recommendations / Robert S. Voss, Philip Myers, François Catzeflis, Ana Paula Carmignotto, and Josefina Barreiro -- Skull and dentition of Willeumys korthi, nov. gen. et sp., a cricetid rodent from the Oligocene (Orellan) of Wyoming / John H. Wahlert.