A new blunt-snouted dyrosaurid, <i>Anthracosuchus balrogus</i> gen. et <b>sp. nov.</b> (Crocodylomorpha, Mesoeucrocodylia), from the Palaeocene of Colombia

<div><p>A new exceptionally brevirostrine dyrosaurid is described from the middle Palaeocene (58–60 million years ago) Cerrejón Formation, northeastern Colombia, based on four partial skulls and associated postcrania. This taxon is unique among dyrosaurids not only in skull shape, but also in having orbital tuberosities, and osteoderms that are dorsoventrally thick and unpitted, a trait otherwise unknown in Crocodylomorpha. Results from a cladistic analysis of Dyrosauridae suggest that the new taxon, together with Cretaceous–Palaeocene <i>Chenanisuchus lateroculi</i> from Africa and <i>Cerrejonisuchus improcerus</i> also from the Cerrejón Formation, are the most basal members of the family. Results from a biogeographic analysis indicate at least three independent dispersals of dyrosaurids from Africa to the New World occurred in the Late Cretaceous or early Palaeocene. Widely set orbits in the new taxon indicate a deviation from surface-based predation, characteristic of other dyrosaurids, to sub-surface predation, as in modern <i>Gavialis</i>. Tooth impressions found on turtle shells recovered from the same locality match well with teeth of the new taxon indicating possible predation.http://www.zoobank.org/urn:lsid:zoobank.org:pub:AB2B24A5-27CC-4D3F-B580-F11F17851CE6</p></div

Tests of different models of character evolution for body mass estimates and calcaneal elongation on six alternative phylogenetic trees relating taxa of this study.

<p>Tests of different models of character evolution for body mass estimates and calcaneal elongation on six alternative phylogenetic trees relating taxa of this study.</p

A new dermatemydid (Testudines, Kinosternoidea) from the Paleocene-Eocene Thermal Maximum, Willwood Formation, southeastern Bighorn Basin, Wyoming

<div><p>ABSTRACT</p><p><i>Gomphochelys nanus</i>, new genus and species, is described from the earliest Wasatchian (biohorizon Wa 0; ∼55.8 Ma) of the southeastern Bighorn Basin, Washakie County, Wyoming. The new taxon represents the only known dermatemydid from the Paleocene–Eocene Thermal Maximum (PETM) interval and extends the lineage back from previous records by approximately 2 million years. <i>Gomphochelys nanus</i> has a thick tricarinate carapace and differs from other dermatemydids in attaining a smaller adult body size, having reduced plastral features, a posteriorly situated gular–humeral sulcus, an acarinate pygal, and thick shortened peripherals. Reexamination of previously described fossil dermatemydids suggests that the taxa <i>Baptemys tricarinata</i> and <i>Kallistira costilata</i> are junior synonyms of the middle–late Wasatchian <i>Notomorpha garmanii</i>, and <i>Baptemys fluviatilis</i> is likely a junior synonym of <i>Baptemys wyomingensis</i>. <i>Gomphochelys nanus</i> is a stem dermatemydid that is similar to <i>N. garmanii</i> but differs in possessing symplesiomorphies with the Late Cretaceous–Paleocene genera <i>Agomphus</i> and <i>Hoplochelys</i>. Aspects of shell morphology suggest that <i>G. nanus</i> was a commensurate swimmer and bottom-walker like extant <i>Dermatemys</i> and <i>Staurotypus</i>. The presence of a dermatemydid (a tropically distributed clade) in the southeastern Bighorn Basin during the PETM (when global temperatures increased by 5°C–10°C over a period of ∼60 ky) further supports the hypothesis that climate was megathermal in the region during this interval and is consistent with previously documented geographic range changes in both plants and animals. Dermatemydids disappear from the fossil record at the end of the PETM and don't reemerge until the next warming event, Eocene Thermal Maximum 2.</p><p>http://zoobank.org/urn:lsid:zoobank.org:pub:19A98079-5CAD-4BC5-8C21-2810AA576D98 </p><p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP</p></div

New early Miocene protoceratids (Mammalia, Artiodactyla) from Panama

<div><p>ABSTRACT</p><p>Although Cenozoic protoceratid artiodactyls are known from throughout North America, species referred to the Miocene protoceratine <i>Paratoceras</i> are restricted to subtropical areas of the Gulf Coast and southern Mexico and tropical areas of Panama. Newly discovered fossils from the late Arikareean Lirio Norte Local Fauna, Panama Canal basin, include partial dentitions of a protoceratid remarkably similar to those of <i>Paratoceras tedfordi</i> from Mexico, suggesting a rapid early Miocene colonization of recently emerged tropical volcanic terrains (Las Cascadas Formation). Partial lower dentitions from the overlying shallow marine to transitional Culebra Formation (early Centenario Fauna) are here referred to <i>Paratoceras orarius</i>, sp. nov., based on relatively small size, shallow mandible anterior to p3, and narrow cheek teeth. New early Hemingfordian protoceratine fossils from the upper part of the Cucaracha Formation (late Centenario Fauna) include a partial male skull and several dentitions that, together with specimens previously referred to <i>P. wardi</i> (only known from the Barstovian of Texas), are here referred to <i>Paratoceras coatesi</i>, sp. nov., based on distinctly more gracile cranial ornamentation, relatively longer nasals, a smaller and wider lower p4 (relative to m1), and more bulbous lower premolars. Results from a cladistic analysis of 15 craniodental characters coded for 11 protoceratine species suggests that <i>Paratoceras</i> is a monophyletic clade with its origin in subtropical areas of Central America, spreading into the tropics of Panama during the early Miocene (Arikareean through Hemingfordian North American Land Mammal Ages [NALMAs]), and later inhabiting subtropical areas of the Gulf Coast during the middle–late Miocene (Barstovian through Clarendonian NALMAs).</p><p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP</p><p>http://zoobank.org/urn:lsid:zoobank.org:pub:31FFF397-6362-443C-A612-E9279FF122</p></div

Coefficients and confidence intervals for ordinary least squares regressions of ln(DL/TL) on estimated ln(BM) in extant and fossil taxa.

*<p>Significant correlation between estimated ln(BM) and ln(DL/TL).</p><p>-Marginally significant or marginally non-significant.</p><p>Abbreviations: abv, sample abbreviation; n, sample size; SE, standard error; int, intercept; r, correlation coefficient; t, student’s t-value; SLCI, slope lower 95% confidence interval; SUCI, slope upper 95% confidence interval; ILCI, intercept lower 95% confidence interval; IUCI, intercept upper 95% confidence interval; P(uncorr), Probability of no correlation; IR 1, intercept residual from slope v. regression equation 1 [including indriids: (intercept) = −7.978 (slope) +0.908]; IR 2, intercept residual from slope v. regression equation 2 [excluding indriids: (intercept) = −7.77 (slope) +0.89].</p

Results of PGLS regressions of distal elongation index [ln(DL/TL)] on ln estimated body mass.

<p>Note that when <b>λ</b> is 0.000, regressions are equivalent to TIPS data (internal branch lengths = 0). Column heading abbreviations: Adj, adjusted; DF, degrees of freedom; Int, y-intercept; P, probability; RSE, Residual Standard Error. Taxon abbreviations: <i>Th, Teilhardina</i>. Trees:1, MP supertree with molecular divergence dates from Springer et al. (2012); 2, MP supertree with fossil dictated early branch lengths; 3, adapiform-haplorhine constraint supertree.</p

Coefficients and confidence intervals for ordinary least squares regressions of ln(DL/TL) on estimated ln(BM) for taxon means.

*<p>Significant correlation between estimated ln(BM) and ln(DL/TL).</p><p>−marginally significant or non-significant.</p><p>Abbreviations: abv, sample abbreviation; n, sample size; SE, standard error; int, intercept; r, correlation coefficient; t, student’s t-value; SLCI, slope lower 95% confidence interval; SUCI, slope upper 95% confidence interval; ILCI, intercept lower 95% confidence interval; IUCI, intercept upper 95% confidence interval; P(uncorr), Probability of no correlation.</p

The biomechanical role of the ankle in leaping with a tarsifulcrumating foot.

<p><b>A</b>, Incremental stages in hind limb extension that accelerates the center of mass in a largely vertical direction in order to produce inertia that carries the animal through the air after the limbs are fully extended. The inset shows the relationship of distal segment (DL) of the calcaneus to the rest of the foot: it forms the “load arm” in a <i>class 2</i> lever system. The lever arm (the heel) comprises the rest of the calcaneal length (TL). <b>B</b>, Measurements used in this study shown on a left calcaneus. Abbreviations: CD, cuboid facet depth; CW, cuboid facet width; TL, total proximodistal length; DL, distal segment length. <b>C</b>, Left feet of primates exhibiting different degrees of leaping specialization scaled to same metatarsus length and aligned at fulcrum of ankle. Taxa that never use leaping behavior have much shorter tarsal bones as shown on the left. The way in which differential degrees of leaping specialization and body-size interact to influence and complicate this relationship is debated <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067792#pone.0067792-MoySol1" target="_blank">[7]</a>.</p

Extant prosimian calcanei exhibit a diversity of sizes and proportions.

<p><b>A</b>, Almost all major prosimian genera are represented at the same scale. <b>B</b>, The same taxa are represented, scaled to length of the proximal segment and arranged (within familial groups) so that the smallest members are on the left, while the largest are on the right. This organization helps one visualize qualitatively, the allometric trends plotted in subsequent figures. Abbreviations: Ac, <i>Arctocebus calabarensis</i>; Al, <i>Avahi laniger</i>; Cma, <i>Cheirogaleus major</i>; Cme, <i>Cheirogaleus medius</i>; Dm, <i>Daubentonia madagascariensis</i>; Ee, <i>Euoticus elegantulus</i>; Ef, <i>Eulemur fulvus</i>; Em, <i>Eulemur mongoz</i>; Gd, <i>Galagoides demidovii</i>; Gs, <i>Galago senegalensis</i>; Hg, <i>Hapalemur griseus</i>; Hs, <i>Hapalemur simus</i>; Ii, <i>Indri indri</i>; Lc, <i>Lemur catta;</i> Lm, <i>Lepilemur mustelinus</i>; Lt, <i>Loris tardigradus</i>; Mc, <i>Mirza coquereli</i>; Mg, <i>Microcebus griseorufus</i>; Nc, <i>Nycticebus coucang</i>; Oc, <i>Otolemur crassicaudatus</i>; Og, <i>Otolemur garnetti</i>; Pp, <i>Perodicticus potto</i>; Pv, <i>Propithecus verreauxi</i>; Vv, <i>Varecia variegata</i>.</p

Plot of fossils with extant forms imposed shows similar allometric scaling relationships characterize in living taxa.

<p>To better understand the phenetic associations of the fossils and to help consider the functional implications of their proportions, we plot them with extant taxa. Each data point represents an individual. Dark gray polygons represent species groups. Light gray polygons bound different extant prosimian radiations: Upper polygon, Galagidae; middle polygon, lemuriformes; lower polygon, Lorisidae. (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067792#pone-0067792-g002" target="_blank">Figures 2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067792#pone-0067792-g003" target="_blank">3</a> for taxon abbreviations). “IVPP” specimens are eosimiids from Shanguang fissure fills with taxon identifications given in Gebo et al. (2000).</p