Bibliography and Index of the Sirenia and Desmostylia  

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"Vélez-Juarbe, Jorge"

Bajpai, Sunil; Domning, Daryl Paul; Das, Debi P.; Vélez-Juarbe, Jorge; Mishra, Vijay P. (detail)
A new fossil sirenian (Mammalia, Dugonginae) from the Miocene of India.
Neues Jb. Geol. Pal. Abh. 258(1): 39-50. 3 tabs. 6 figs. Published online June 2010.
–Describes Kutchisiren cylindrica, n.gen.n.sp., from the Lower Miocene (Aquitanian or Burdigalian) Khari Nadi Formation of Kutch, Gujarat, western India.
Uhen, Mark David; Coates, Anthony G.; Jaramillo, Carlos A.; Montes, Camilo; Pimiento, Catalina; Rincón, Aldo; Strong, Nikki; Vélez-Juarbe, Jorge (detail)
Marine mammals from the Miocene of Panama.
Jour. South American Earth Scis. 30(3-4): 167-175. 2 tabs. 5 figs.
–Describes a caudal vertebra and rib fragments representing two different dugongids from the Early Mioc. (Aquitanian-Burdigalian) Culebra Formation, Panama Canal (167-168, 170-174).
Vélez-Juarbe, Jorge; Domning, Daryl Paul; Pyenson, Nicholas D. (detail)
Iterative evolution of sympatric seacow (Dugongidae, Sirenia) assemblages during the past ~26 million years.
PLoS ONE 7(2): e31294. 8 pp. 1 tab. 3 figs. + 1 fig. in Supporting Information. DOI:10.1371/journal.pone.0031294. Feb. 3, 2012.
–Available online at:
 ABSTRACT: Extant sirenians show allopatric distributions throughout most of their range. However, their fossil record shows evidence of multispecies communities throughout most of the past ~26 million years, in different oceanic basins. Morphological differences among co-occurring sirenian taxa suggest that resource partitioning played a role in structuring these communities. We examined body size and ecomorphological differences (e.g., rostral deflection and tusk morphology) among sirenian assemblages from the late Oligocene of Florida, early Miocene of India and early Pliocene of Mexico; each with three species of the family Dugongidae. Although overlapping in several ecomorphological traits, each assemblage showed at least one dominant trait in which coexisting species differed. Fossil sirenian occurrences occasionally are monotypic, but the assemblages analyzed herein show iterative evolution of multispecies communities, a phenomenon unparalleled in extant sirenian ecology. As primary consumers of seagrasses, these communities likely had a strong impact on past seagrass ecology and diversity, although the sparse fossil record of seagrasses limits direct comparisons. Nonetheless, our results provide robust support for previous suggestions that some sirenians in these extinct assemblages served as keystone species, controlling the dominance of climax seagrass species, permitting more taxonomically diverse seagrass beds (and sirenian communities) than many of those observed today.
Veléz-Juarbe, Jorge; Noriega, Jorge I.; Ferrero, Brenda S. (detail)
Fossil Dugongidae (Mammalia, Sirenia) from the Parana Formation (late Miocene) of Entre Rios Province, Argentina.
Ameghiniana 49(4): 585-593. 1 tab. 4 figs.
–Spanish summ.
Fitzgerald, Erich M. G.; Vélez-Juarbe, Jorge; Wells, Roderick T. (detail)
Miocene sea cow (Sirenia) from Papua New Guinea sheds light on sirenian evolution in the Indo-Pacific.
Jour. Vert. Paleo. 33(4): 956-963. 2 tabs. 8 figs. July 2013.
Vélez-Juarbe, Jorge (detail)
Ghost of seagrasses past: using sirenians as a proxy for historical distribution of seagrasses.
Palaeogeogr. Palaeoclim. Palaeoecol. 400: 41-49. 1 tab. 4 figs. Apr. 15, 2014.
–ABSTRACT: Seagrasses are a notable component of shallow marine habitats, especially in tropical and subtropical regions. Their fossil record extends back to the Mesozoic, but it is relatively poor and fragmentary, with large temporal and geographical gaps. As a result, very little is known about the paleobiogeography of these plants and how physical drivers, such as climatic or oceanic events, have affected their distribution. One approach is to infer the past distribution of seagrasses using fossils of organisms dependent of seagrasses with more complete records as proxies.
  Seagrass consumers, such as sirenians (seacows, manatees and dugongs), are much better represented in the fossil record than seagrasses are. The characteristically dense bones of sirenians together with the fact that they are usually found in marginal marine environments increases the potential for preservation and recognition of their fossils. The long evolutionary history of sirenians, extending throughout most of the last 50 Ma, together with their diet permits the use of their fossils as a proxy for inferring the paleobiogeography of seagrasses.
  Here I looked at the fossil record of sirenians and seagrasses from the Eocene, through the Miocene epochs. This comparison produced several inferences about seagrass paleobiogeography and how physical drivers, such as climate change, ocean currents and tectonic events, have been influential in their distribution: 1) seagrasses were well-established in the Western Atlantic–Caribbean prior to the middle Eocene, making possible at least two instances of trans-Atlantic sirenian dispersal events, either with the aid of Tethyan currents or along the nearly continuous Northern Atlantic coastline that was present in the Eocene; 2) climatic cooling during the early Oligocene seemed to have limited the extent of seagrasses and sirenians, although these groups recovered and further diversified and expanded their distributions by the late Oligocene in tandem with a climatic warming event; 3) by the Miocene, seagrasses and sirenians reached the southern Western Atlantic and the Eastern Pacific aided by the presence of the Central American Seaway, achieving a distribution similar to, and sometimes, surpassing that of today. The fossil record of sirenians can provide a broad overview of seagrass paleobiogeography through time. However, several aspects, such as when sirenians and seagrasses arrived to Australia and the seemingly late arrival of seagrasses to South America and the Eastern Pacific, still need further investigation.
Vélez-Juarbe, Jorge; Domning, Daryl Paul (detail)
Fossil Sirenia of the West Atlantic and Caribbean region. IX. Metaxytherium albifontanum, sp. nov.
Journal of Vertebrate Paleontology 34(2): 444-464. 11 tabs. 15 figs. + supplemental online material. Mar. 2014 (publ. online Mar. 4, 2014).
–ABSTRACT: We describe a new species of the halitheriine dugongid genus Metaxytherium from the late Oligocene of Florida and South Carolina. The new species is represented by cranial and postcranial material, including parts of the axial and appendicular skeleton. Metaxytherium albifontanum, sp. nov., differs from other species of Metaxytherium by the following unique combination of plesiomorphic and derived characters: posterior end of nasal process of premaxilla broad and flat relative to what is observed in most other members of the genus (somewhat resembling M. subapenninum); ventral extremity of jugal under posterior edge of orbit (character 85[1]) (shared with M. krahuletzi); exoccipitals separated in dorsal midline (character 66[1]) (shared with all other species in the genus, except some M. krahuletzi); and innominate with acetabulum (nearly lost or lost in M. crataegense, M. floridanum, M. serresii). This new species was sympatric with two dugongines, Crenatosiren olseni and Dioplotherium manigaulti. The small tusks and cranial morphology of M. albifontanum, sp. nov., indicate that it was likely a consumer of small seagrasses. Our phylogenetic analysis is consistent with previous ones in placing Hydrodamalinae within a paraphyletic Metaxytherium spp. and placing the Metaxytherium spp. + Hydrodamalinae clade as the sister group to Dugonginae. Metaxytherium albifontanum, sp. nov., is the oldest known member of its genus; this might indicate that the group originated in the West Atlantic and Caribbean region and later dispersed to the Old World Tethys region.
Vélez-Juarbe, Jorge; Domning, Daryl Paul (detail)
Fossil Sirenia of the West Atlantic and Caribbean region: X. Priscosiren atlantica, gen. et sp. nov.
Journal of Vertebrate Paleontology 34(4): 951-964. 4 tabs. 9 figs. July 2014 (publ. online July 8, 2014).
–ABSTRACT: We describe a new genus and species of early Oligocene halitheriine dugongid from the Western Atlantic region. Priscosiren atlantica, gen. et sp. nov., differs from all other halitheriine dugongids by displaying the following unique combination of characters: supraorbital processes dorsoventrally thin (?1 cm) with well-developed prominent posterolateral corner; supraoccipitals wider in the dorsal half than the ventral half; exoccipitals meeting dorsal to the foramen magnum; posttympanic process with a prominent anteroventral process for attachment of m. sternomastoideus; nasals separated in midline; ventral extremity of jugal located ventral to orbit; ventral border of mandible strongly concave; absence of accessory mental foramina; dorsoventrally broad horizontal ramus of mandible; loss of all permanent premolars; and concave anteroventral surface of jugal (a possible autapomorphy). Differs further from the similar species Caribosiren turneri in having lesser rostral deflection (of about 44°); presence of small incisors; lower temporal crests; and slightly larger body size. The relationship of Priscosiren with other dugongids places it close to being a structural as well as temporal ancestor to the Metaxytherium + Hydrodamalinae and Dugonginae clades. This supports previous assumptions of a Western Atlantic and Caribbean origin for these groups, and indicates that the halitheriine-dugongine divergence must have occurred no later than the earliest Oligocene. Priscosiren, Caribosiren, and Crenatosiren evidently coexisted in the West Atlantic–Caribbean region, and constitute yet another case of a uniquely patterned fossil sirenian multispecies community.
Springer, Mark S.; Signore, Anthony V.; Paijmans, Johanna L. A.; Vélez-Juarbe, Jorge; Domning, Daryl Paul; Bauer, Cameron E.; He, Kai; Crerar, Lorelei D.; Campos, Paula F.; Murphy, William J.; Meredith, Robert W.; Gatesy, John; Willerslev, Eske; MacPhee, Ross D. E.; Hofreiter, Michael; Campbell, Kevin L. (detail)
Interordinal gene capture, the phylogenetic position of Steller's sea cow based on molecular and morphological data, and the macroevolutionary history of Sirenia.
Molecular Phylogenetics & Evolution 91: 178-193. 5 tabs. 5 figs. 9 tabs. in online Supplementary Material. DOI:10.1016/j.ympev.2015.05.022 Publ. online June 4, 2015.
–ABSTRACT: The recently extinct (ca. 1768) Steller's sea cow (Hydrodamalis gigas) was a large, edentulous North Pacific sirenian. The phylogenetic affinities of this taxon to other members of this clade, living and extinct, are uncertain based on previous morphological and molecular studies. We employed hybridization capture methods and second generation sequencing technology to obtain >30 kb of exon sequences from 26 nuclear genes for both H. gigas and Dugong dugon. We also obtained complete coding sequences for the tooth-related enamelin (ENAM) gene. Hybridization probes designed using dugong and manatee sequences were both highly effective in retrieving sequences from H. gigas (mean = 98.8% coverage), as were more divergent probes for regions of ENAM (99.0% coverage) that were designed exclusively from a proboscidean (African elephant) and a hyracoid (Cape hyrax). New sequences were combined with available sequences for representatives of all other afrotherian orders. We also expanded a previously published morphological matrix for living and fossil Sirenia by adding both new taxa and nine new postcranial characters. Maximum likelihood and parsimony analyses of the molecular data provide robust support for an association of H. gigas and D. dugon to the exclusion of living trichechids (manatees). Parsimony analyses of the morphological data also support the inclusion of H. gigas in Dugongidae with D. dugon and fossil dugongids. Timetree analyses based on calibration density approaches with hard- and soft-bounded constraints suggest that H. gigas and D. dugon diverged in the Oligocene and that crown sirenians last shared a common ancestor in the Eocene. The coding sequence for the ENAM gene in H. gigas does not contain frameshift mutations or stop codons, but there is a transversion mutation (AG to CG) in the acceptor splice site of intron 2. This disruption in the edentulous Steller's sea cow is consistent with previous studies that have documented inactivating mutations in tooth-specific loci of a variety of edentulous and enamelless vertebrates including birds, turtles, aardvarks, pangolins, xenarthrans, and baleen whales. Further, branch-site dN/dS analyses provide evidence for positive selection in ENAM on the stem dugongid branch where extensive tooth reduction occurred, followed by neutral evolution on the Hydrodamalis branch. Finally, we present a synthetic evolutionary tree for living and fossil sirenians showing several key innovations in the history of this clade including character state changes that parallel those that occurred in the evolutionary history of cetaceans.
Vélez-Juarbe, Jorge; Domning, Daryl Paul (detail)
Fossil Sirenia of the West Atlantic and Caribbean region. XI. Callistosiren boriquensis, gen. et sp. nov.
Journal of Vertebrate Paleontology 35(1): e885034 (16 pp.). 4 tabs. 11 figs. DOI: 10.1080/02724634.2014.885034 Jan. 2015 (publ. online Jan. 26, 2015).
–Spanish summ.
  ABSTRACT: Here we describe a new taxon of late Oligocene dugongine from the Western Atlantic and Caribbean region. Known from cranial and postcranial material, Callistosiren boriquensis, gen. et sp. nov., differs from other members of the group by displaying the following unique combination of characters: nasal process of premaxilla tapering but thickened; supraorbital process of frontal dorsoventrally thin (<2 cm) and well developed with recurved, bluntly pointed posterolateral corner; ventral rim of orbit not overhanging the lateral surface of the jugal; pterygoid fossa tall; tusks large, lozenge- or kite-shaped in cross-section, and with enamel confined to the medial side; lacrimals with thin, elongated dorsal process that is wedged between the premaxilla and frontal; and osteosclerotic but minimally pachyostotic ribs and vertebrae. A phylogenetic analysis places Callistosiren as one of the more basal members of the Dugonginae, but we note that the relationships and taxonomy of more derived members are in need of revision. Characters of the cranial morphology, such as the shape and size of the incisor tusks and the nature of the contact between the premaxilla and frontal, indicate that this new taxon may have fed preferentially on large species of seagrasses and their rhizomes. In addition, possession of osteosclerotic but minimally pachyostotic ribs and vertebrae is a unique feature unknown in other extinct dugongines and may indicate foraging behavior not known from other fossil sirenians.

Daryl P. Domning, Research Associate, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, and Laboratory of Evolutionary Biology, Department of Anatomy, College of Medicine, Howard University, Washington, D.C. 20059.
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