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Leonardo Dos Santos Avilla - One of the best experts on this subject based on the ideXlab platform.

  • What Is Equus? Reconciling Taxonomy and Phylogenetic Analyses
    Frontiers in Ecology and Evolution, 2019
    Co-Authors: Christina I. Barrón-ortiz, Leonardo Dos Santos Avilla, Christopher N. Jass, Victor M. Bravo-cuevas, Helena Machado, Dimila Mothé
    Abstract:

    Interest in the origin and evolution of Equus dates back to over a century, but there is still no consensus on the definition of the genus or its phylogenetic position. We review the placement of Equus within several phylogenetic frameworks and present a phylogenetic analysis of derived Equini, including taxa referred to Equus, Haringtonhippus, Dinohippus, Astrohippus, Hippidion, and Boreohippidion. A new, morphology-based phylogenetic tree was used as an initial hypothesis for discussing what taxa Equus encompasses, using four criteria previously used to define the genus category in mammals: phylogenetic gaps, uniqueness of adaptive zone, crown group definition, and divergence time. According to the phylogenetic gaps criterion, Equus encompasses clade 6 (Ha. francisci = E. francisci, E. conversidens, E. quagga, E. hemionus, E. mexicanus, E. ferus, E. occidentalis, and E. neogeus) based on morphological synapomorphies. Equus is assigned to clade 6, or possibly clade 7, according to the uniqueness of adaptive zone criterion. The crown group criterion places Equus at clade 6. Based on the time-calibrated phylogeny of Equini, the divergence time criterion suggests that Equus encompasses clade 9. This clade comprises all taxa traditionally assigned to Equus analyzed in our study, including the eight taxa listed above as well as E. stenonis, E. idahoensis, and E. simplicidens; the latter two are sometimes referred to the subgenus Plesippus and the former to the subgenus Allohippus. With the exception of the divergence time criterion, the results of our evaluation are congruent in identifying clade 6 as the most suitable position for Equus. The taxonomic implications of delimiting Equus to clade 6 in our phylogenetic tree include elevation of Allohippus and Plesippus to generic rank, assignment of a new genus to “Dinohippus” mexicanus, and synonymy of Haringtonhippus with Equus.

  • The Diversity of South American Equus: Did Size Really Matter?
    Frontiers in Ecology and Evolution, 2019
    Co-Authors: Helena Machado, Leonardo Dos Santos Avilla
    Abstract:

    The Equus has a North American origin probably during the transition Miocene/Pliocene, and its entrance in South America is possibly related to one of the latest four events of the Great American Biotic Interchange. Nonetheless, the genus presented broad geographic distribution throughout South America. Traditionally, there were five species of Equus recognized to this continent and just recently they have been synonymized into three: Equus neogeus, E. insulatus and E. andium. However, their diagnoses are still unclear and a recent study showed that characters previously used are not taxonomically valid to distinguish such diversity, being inferred that in South America the genus was represented by a single species, E. neogeus. This contribution intends to update the knowledge of the diversity of South American Equus. In this sense, a synthesis of what is known so far as well as an update of the fossil record is presented here. Dental analyses were made and the results revealed a clear superimposition within the species. Also, autopodia characters were reanalyzed with greater sampling and the results once again corroborated that there was a single species presented in South America. The update of occurrences of the fossil record increased the knowledge of the geographical distribution of the genus in South America. There are records throughout almost all the continent, except for regions in the Amazon Forest, below latitude 40°, and altitudes above 3000m. Furthermore, its geographical distribution pattern along with the new incoming data revealed that E. neogeus fit as a smooth cline, in which the variation is gradual and continuous. It is also inferred that the phenotypic variation observed is probably related to the type of relief conformation.

  • Following the Footsteps of the South American Equus: Are Autopodia Taxonomically Informative?
    Journal of Mammalian Evolution, 2017
    Co-Authors: Helena Machado, Eric Scott, Orlando N. Grillo, Leonardo Dos Santos Avilla
    Abstract:

    The genus Equus originated in the Pliocene Epoch of North America, and its arrival in South America is likely related to the Great American Biotic Interchange that took place in the transition of Pliocene to Pleistocene. Currently, there are five recognized species for the South American continent: Equus neogeus, E. santaeelenae, E. insulatus, E. andium, and E. lasallei. The taxonomy of the genus is traditionally based in part upon the proportions of the autopodia. The aim of this study is to evaluate the diagnostic importance of the autopodia of South American Equus through comparative and multiple statistical analyses. Therefore, we analyzed metacarpals, metatarsals, and phalanges from all available South American Equus, with the exception of E. lasallei, which is only known by a skull. We also examined the North American species E. occidentalis, as it has been interpreted to be closely related to South American Equus. Results showed no significant differences between the various South American species according to the dimensions and proportions of the autopodia. A continuum of gradual linear variation among the species was revealed, with superimposition between autopodial characters. The succession and overlap of species indicated that the South American Equus might represent a type of cline.

Bruce J. Macfadden - One of the best experts on this subject based on the ideXlab platform.

  • Horses in the cloud; big data exploration and mining of fossil and extant Equus (Mammalia, Equidae)
    Paleobiology, 2016
    Co-Authors: Bruce J. Macfadden, Robert P. Guralnick
    Abstract:

    Abstract. Extant species of the genus Equus (e.g., horses, asses, and zebras) have a widespread distribution today on all continents except Antarctica. Extinct species of Equus represented by fossils were likewise widely distributed in the Pliocene and even more so during the Pleistocene. In order to understand the efficacy of “big data” for (paleo)biogeographic analyses, location records (latitude, longitude) and fossil occurrences for the genus Equus were mined and further explored from six databases, including iDigBio, Paleobiology Database, VertNet, BISON, Neotoma, and GBIF. These were chosen from a priori knowledge of where relevant data might be aggregated. We also realized that these databases have different objectives and data sources and therefore would provide a useful comparative study of the widespread taxon Equus in space and time. The mining of Equus data from these six sources yielded a combined total of 123.8 K location records, including 116.2K fossil specimens. These include individual p...

  • Dispersal of Pleistocene Equus (Family Equidae) into South America and calibration of GABI 3 based on evidence from Tarija, Bolivia.
    PloS one, 2013
    Co-Authors: Bruce J. Macfadden
    Abstract:

    The dispersal of Equus into South America during the Great American Biotic Interchange (GABI) represented a major event for Pleistocene land-mammal age chronology on that continent. It has been argued that this dispersal occurred during the late Pleistocene, ∼0.125 Ma, and it defines the base of the Lujanian South American Land Mammal Age (SALMA). In this scenario, Equus dispersed during the fourth and latest recognized phase of the interchange, i.e., GABI 4. Although Equus was widely distributed in South America during the Pleistocene, only a few localities are calibrated by independent chronostratigraphic data. In this paper, new biostratigraphic evidence documents that Equus occurs from 15 superposed faunal horizons or zones throughout the Tolomosa Formation at Tarija, Bolivia. This biostratigraphic sequence is independently calibrated to occur between ∼0.99 to

Machteld C Van Dierendonck - One of the best experts on this subject based on the ideXlab platform.

  • Monitoring Acute Pain in Donkeys with the Equine Utrecht University Scale for Donkeys Composite Pain Assessment (Equus-DONKEY-COMPASS) and the Equine Utrecht University Scale for Donkey Facial Assessment of Pain (Equus-DONKEY-FAP).
    Animals : an open access journal from MDPI, 2020
    Co-Authors: Machteld C Van Dierendonck, Faith Burden, Karen Rickards, Johannes P A M Van Loon
    Abstract:

    Objective pain assessment in donkeys is of vital importance for improving welfare in a species that is considered stoic. This study presents the construction and testing of two pain scales, the Equine Utrecht University Scale for Donkey Composite Pain Assessment (Equus-DONKEY-COMPASS) and the Equine Utrecht University Scale for Donkey Facial Assessment of Pain (Equus-DONKEY-FAP), in donkeys with acute pain. A cohort follow-up study using 264 adult donkeys (n = 12 acute colic, n = 25 acute orthopaedic pain, n = 18 acute head-related pain, n = 24 postoperative pain, and n = 185 controls) was performed. Both pain scales showed differences between donkeys with different types of pain and their control animals (p < 0.001). The Equus-DONKEY-COMPASS and Equus-DONKEY-FAP showed high inter-observer reliability (Cronbach’s alpha = 0.97 and 0.94, respectively, both p < 0.001). Sensitivity of the Equus-DONKEY-COMPASS was good for colic and orthopaedic pain (83% and 88%, respectively), but poor for head-related and postoperative pain (17% and 21%, respectively). Sensitivity of the Equus-DONKEY-FAP was good for colic and head-related pain (75% and 78%, respectively), but moderate for orthopaedic and postoperative pain (40% and 50%, respectively). Specificity was good for all types of pain with both scales (91%–99%). Different types of acute pain in donkeys can be validly assessed by either a composite or a facial expression-based pain scale.

  • monitoring equine head related pain with the equine utrecht university scale for facial assessment of pain Equus fap
    Veterinary Journal, 2017
    Co-Authors: Johannes P A M Van Loon, Machteld C Van Dierendonck
    Abstract:

    This study validates a recently described pain scale, the Equine Utrecht University scale for facial assessment of pain (Equus-FAP), in horses with acute or postoperative pain originating from the head, including dental pain, ocular pain, or trauma to the skull. This cohort study of 23 horses with head-related pain and 23 normal, healthy controls revealed significant differences in Equus-FAP scores between control horses and horses with acute or postoperative pain (P <0.001). Moreover, pain scores after surgery decreased significantly over time (P <0.001). The scale showed good inter-observer reliability (intra-class correlation coefficient = 0.92), sensitivity (80%), specificity (78%), and positive (80%) and negative predictive values (78%).

  • monitoring acute equine visceral pain with the equine utrecht university scale for composite pain assessment Equus compass and the equine utrecht university scale for facial assessment of pain Equus fap a scale construction study
    Veterinary Journal, 2015
    Co-Authors: Johannes P A M Van Loon, Machteld C Van Dierendonck
    Abstract:

    Although recognition of equine pain has been studied extensively over the past decades there is still need for improvement in objective identification of pain in horses with acute colic. This study describes scale construction and clinical applicability of the Equine Utrecht University Scale for Composite Pain Assessment (Equus-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (Equus-FAP) in horses with acute colic. A cohort follow-up study was performed using 50 adult horses (n = 25 with acute colic, n = 25 controls). Composite pain scores were assessed by direct observations, Visual Analog Scale (VAS) scores were assessed from video clips. Colic patients were assessed at arrival, and on the first and second mornings after arrival. Both the Equus-COMPASS and Equus-FAP scores showed high inter-observer reliability (ICC = 0.98 for Equus-COMPASS, ICC = 0.93 for Equus-FAP, P <0.001), while a moderate inter-observer reliability for the VAS scores was found (ICC = 0.63, P <0.001). The cut-off value for differentiation between healthy and colic horses for the Equus-COMPASS was 5, and for differentiation between conservatively treated and surgically treated or euthanased patients it was 11. For the Equus-FAP, cut-off values were 4 and 6, respectively. Internal sensitivity and specificity were good for both Equus-COMPASS (sensitivity 95.8%, specificity 84.0%) and Equus-FAP (sensitivity 87.5%, specificity 88.0%). The use of the Equus-COMPASS and Equus-FAP enabled repeated and objective scoring of pain in horses with acute colic. A follow-up study with new patients and control animals will be performed to further validate the constructed scales that are described in this study.

  • Monitoring acute equine visceral pain with the Equine Utrecht University Scale for Composite Pain Assessment (Equus-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (Equus-FAP): A scale-construction study.
    Veterinary journal (London England : 1997), 2015
    Co-Authors: Johannes P A M Van Loon, Machteld C Van Dierendonck
    Abstract:

    Although recognition of equine pain has been studied extensively over the past decades there is still need for improvement in objective identification of pain in horses with acute colic. This study describes scale construction and clinical applicability of the Equine Utrecht University Scale for Composite Pain Assessment (Equus-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (Equus-FAP) in horses with acute colic. A cohort follow-up study was performed using 50 adult horses (n = 25 with acute colic, n = 25 controls). Composite pain scores were assessed by direct observations, Visual Analog Scale (VAS) scores were assessed from video clips. Colic patients were assessed at arrival, and on the first and second mornings after arrival. Both the Equus-COMPASS and Equus-FAP scores showed high inter-observer reliability (ICC = 0.98 for Equus-COMPASS, ICC = 0.93 for Equus-FAP, P

Helena Machado - One of the best experts on this subject based on the ideXlab platform.

  • What Is Equus? Reconciling Taxonomy and Phylogenetic Analyses
    Frontiers in Ecology and Evolution, 2019
    Co-Authors: Christina I. Barrón-ortiz, Leonardo Dos Santos Avilla, Christopher N. Jass, Victor M. Bravo-cuevas, Helena Machado, Dimila Mothé
    Abstract:

    Interest in the origin and evolution of Equus dates back to over a century, but there is still no consensus on the definition of the genus or its phylogenetic position. We review the placement of Equus within several phylogenetic frameworks and present a phylogenetic analysis of derived Equini, including taxa referred to Equus, Haringtonhippus, Dinohippus, Astrohippus, Hippidion, and Boreohippidion. A new, morphology-based phylogenetic tree was used as an initial hypothesis for discussing what taxa Equus encompasses, using four criteria previously used to define the genus category in mammals: phylogenetic gaps, uniqueness of adaptive zone, crown group definition, and divergence time. According to the phylogenetic gaps criterion, Equus encompasses clade 6 (Ha. francisci = E. francisci, E. conversidens, E. quagga, E. hemionus, E. mexicanus, E. ferus, E. occidentalis, and E. neogeus) based on morphological synapomorphies. Equus is assigned to clade 6, or possibly clade 7, according to the uniqueness of adaptive zone criterion. The crown group criterion places Equus at clade 6. Based on the time-calibrated phylogeny of Equini, the divergence time criterion suggests that Equus encompasses clade 9. This clade comprises all taxa traditionally assigned to Equus analyzed in our study, including the eight taxa listed above as well as E. stenonis, E. idahoensis, and E. simplicidens; the latter two are sometimes referred to the subgenus Plesippus and the former to the subgenus Allohippus. With the exception of the divergence time criterion, the results of our evaluation are congruent in identifying clade 6 as the most suitable position for Equus. The taxonomic implications of delimiting Equus to clade 6 in our phylogenetic tree include elevation of Allohippus and Plesippus to generic rank, assignment of a new genus to “Dinohippus” mexicanus, and synonymy of Haringtonhippus with Equus.

  • The Diversity of South American Equus: Did Size Really Matter?
    Frontiers in Ecology and Evolution, 2019
    Co-Authors: Helena Machado, Leonardo Dos Santos Avilla
    Abstract:

    The Equus has a North American origin probably during the transition Miocene/Pliocene, and its entrance in South America is possibly related to one of the latest four events of the Great American Biotic Interchange. Nonetheless, the genus presented broad geographic distribution throughout South America. Traditionally, there were five species of Equus recognized to this continent and just recently they have been synonymized into three: Equus neogeus, E. insulatus and E. andium. However, their diagnoses are still unclear and a recent study showed that characters previously used are not taxonomically valid to distinguish such diversity, being inferred that in South America the genus was represented by a single species, E. neogeus. This contribution intends to update the knowledge of the diversity of South American Equus. In this sense, a synthesis of what is known so far as well as an update of the fossil record is presented here. Dental analyses were made and the results revealed a clear superimposition within the species. Also, autopodia characters were reanalyzed with greater sampling and the results once again corroborated that there was a single species presented in South America. The update of occurrences of the fossil record increased the knowledge of the geographical distribution of the genus in South America. There are records throughout almost all the continent, except for regions in the Amazon Forest, below latitude 40°, and altitudes above 3000m. Furthermore, its geographical distribution pattern along with the new incoming data revealed that E. neogeus fit as a smooth cline, in which the variation is gradual and continuous. It is also inferred that the phenotypic variation observed is probably related to the type of relief conformation.

  • Following the Footsteps of the South American Equus: Are Autopodia Taxonomically Informative?
    Journal of Mammalian Evolution, 2017
    Co-Authors: Helena Machado, Eric Scott, Orlando N. Grillo, Leonardo Dos Santos Avilla
    Abstract:

    The genus Equus originated in the Pliocene Epoch of North America, and its arrival in South America is likely related to the Great American Biotic Interchange that took place in the transition of Pliocene to Pleistocene. Currently, there are five recognized species for the South American continent: Equus neogeus, E. santaeelenae, E. insulatus, E. andium, and E. lasallei. The taxonomy of the genus is traditionally based in part upon the proportions of the autopodia. The aim of this study is to evaluate the diagnostic importance of the autopodia of South American Equus through comparative and multiple statistical analyses. Therefore, we analyzed metacarpals, metatarsals, and phalanges from all available South American Equus, with the exception of E. lasallei, which is only known by a skull. We also examined the North American species E. occidentalis, as it has been interpreted to be closely related to South American Equus. Results showed no significant differences between the various South American species according to the dimensions and proportions of the autopodia. A continuum of gradual linear variation among the species was revealed, with superimposition between autopodial characters. The succession and overlap of species indicated that the South American Equus might represent a type of cline.

Kate Jirik - One of the best experts on this subject based on the ideXlab platform.