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Bertrand OC, Jiménez Lao M, Shelley SL, Wible JR, Williamson TE, Meng J, Brusatte SL. The virtual brain endocast of Trogosus (Mammalia, Tillodontia) and its relevance in understanding the extinction of archaic placental mammals. J Anat 2024; 244:1-21. [PMID: 37720992 PMCID: PMC10734658 DOI: 10.1111/joa.13951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/19/2023] Open
Abstract
After successfully diversifying during the Paleocene, the descendants of the first wave of mammals that survived the end-Cretaceous mass extinction waned throughout the Eocene. Competition with modern crown clades and intense climate fluctuations may have been part of the factors leading to the extinction of these archaic groups. Why these taxa went extinct has rarely been studied from the perspective of the nervous system. Here, we describe the first virtual endocasts for the archaic order Tillodontia. Three species from the middle Eocene of North America were analyzed: Trogosus hillsii, Trogosus grangeri, and Trogosus castoridens. We made morphological comparisons with the plaster endocast of another tillodont, Tillodon fodiens, as well as groups potentially related to Tillodontia: Pantodonta, Arctocyonidae, and Cimolesta. Trogosus shows very little inter-specific variation with the only potential difference being related to the fusion of the optic canal and sphenorbital fissure. Many ancestral features are displayed by Trogosus, including an exposed midbrain, small neocortex, orbitotemporal canal ventral to rhinal fissure, and a broad circular fissure. Potential characteristics that could unite Tillodontia with Pantodonta, and Arctocyonidae are the posterior position of cranial nerve V3 exit in relation to the cerebrum and the low degree of development of the subarcuate fossa. The presence of large olfactory bulbs and a relatively small neocortex are consistent with a terrestrial lifestyle. A relatively small neocortex may have put Trogosus at risk when competing with artiodactyls for potentially similar resources and avoiding predation from archaic carnivorans, both of which are known to have had larger relative brain and neocortex sizes in the Eocene. These factors may have possibly exacerbated the extinction of Tillodontia, which showed highly specialized morphologies despite the increase in climate fluctuations throughout the Eocene, before disappearing during the middle Eocene.
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Affiliation(s)
- Ornella C Bertrand
- Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici ICTA-ICP, Cerdanyola del Vallès, Barcelona, Spain
- School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, Scotland, UK
| | - Marina Jiménez Lao
- School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, Scotland, UK
| | - Sarah L Shelley
- School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, Scotland, UK
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA
| | - John R Wible
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA
| | - Thomas E Williamson
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
| | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, New York, USA
| | - Stephen L Brusatte
- School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, Scotland, UK
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
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2
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Rust K, Ni X, Tietjen K, Beard KC. Phylogeny and paleobiogeography of the enigmatic North American primate Ekgmowechashala illuminated by new fossils from Nebraska (USA) and Guangxi Zhuang Autonomous Region (China). J Hum Evol 2023; 185:103452. [PMID: 37935595 DOI: 10.1016/j.jhevol.2023.103452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 11/09/2023]
Abstract
Ekgmowechashala is a poorly documented but very distinctive primate known only from the late early Oligocene (early Arikareean) of western North America. Because of its highly autapomorphous dentition and spatiotemporal isolation, the phylogenetic and biogeographic affinities of Ekgmowechashala have long been debated. Here, we describe the oldest known fossils of Ekgmowechashala from the Brown Siltstone Beds of the Brule Formation, White River Group of western Nebraska. We also describe a new ekgmowechashaline taxon from the Nadu Formation (late Eocene) in the Baise Basin of Guangxi Zhuang Autonomous Region in southern China. Phylogenetic analysis suggests that North American Ekgmowechashala and the new Chinese taxon are sister taxa that are nested within a radiation of southern Asian adapiforms that also includes Gatanthropus, Muangthanhinius, and Bugtilemur. The new Chinese ekgmowechashaline helps fill the considerable disparity in dental morphology between Ekgmowechashala and more primitive ekgmowechashalids known from southern Asia. Our study underscores the fundamental role of southern Asia as a refugium for multiple primate clades during the cooler and drier climatic regime that prevailed after the Eocene-Oligocene transition. The colonization of North America by Ekgmowechashala helps define the beginning of the Arikareean Land Mammal Age and corresponds to an example of the Lazarus effect, whereby a taxon (in this case, the order Primates) reappears suddenly in the fossil record after a lengthy hiatus.
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Affiliation(s)
- Kathleen Rust
- Biodiversity Institute, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS, 66045-7561, USA; Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7561, USA
| | - Xijun Ni
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate, Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing, 100044, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Kristen Tietjen
- Biodiversity Institute, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS, 66045-7561, USA
| | - K Christopher Beard
- Biodiversity Institute, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS, 66045-7561, USA; Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7561, USA.
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3
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White CL, Bloch JI, Morse PE, Silcox MT. Virtual endocast of late Paleocene Niptomomys (Microsyopidae, Euarchonta) and early primate brain evolution. J Hum Evol 2023; 175:103303. [PMID: 36608392 DOI: 10.1016/j.jhevol.2022.103303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 01/05/2023]
Abstract
Paleogene microsyopid plesiadapiforms are among the oldest euarchontans known from relatively complete crania. While cranial endocasts are known for larger-bodied Eocene microsyopine microsyopids, this study documents the first virtual endocast for the more diminutive uintasoricine microsyopids, derived from a specimen of Niptomomys cf. Niptomomys doreenae (USNM 530198) from the late Paleocene of Wyoming. Size estimates of smaller-bodied uintasoricines are similar to those inferred for the common ancestor of Primates, so the virtual endocast of Niptomomys may provide a useful model to study early primate brain evolution. Due to the broken and telescoped nature of the neurocranium of USNM 530198, a μCT scan of the specimen was used to create a 3D model of multiple bone fragments that were then independently isolated, repositioned, and merged to form a cranial reconstruction from which a virtual endocast was extracted. The virtual endocast of Niptomomys has visible caudal colliculi, suggesting less caudal expansion of the cerebrum compared to that of euprimates, but similar to that of several other plesiadapiforms. The part of the endocast representing the olfactory bulbs is larger relative to overall endocast volume in Niptomomys (8.61%) than that of other known plesiadapiforms (∼5%) or euprimates (<3.5%). The petrosal lobules (associated with visual stabilization) are relatively large for a Paleocene placental mammal (1.66%). The encephalization quotient of Niptomomys is relatively high (range = 0.35-0.85) compared to that of Microsyops (range = 0.32-0.52), with the upper estimates in the range of values calculated for early euprimates. However, this contrast likely relates in part to the small size of the taxon, and is not associated with evidence of neocortical expansion. These findings are consistent with a model of shifting emphasis in primate evolution toward functions of the cerebrum and away from olfaction with the origin of euprimates.
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Affiliation(s)
- Chelsea L White
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4, Canada
| | - Jonathan I Bloch
- Florida Museum of Natural History, University of Florida, P.O. Box 117800, Gainesville, FL, 32611-7800, USA
| | - Paul E Morse
- Florida Museum of Natural History, University of Florida, P.O. Box 117800, Gainesville, FL, 32611-7800, USA; Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4, Canada.
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Bertrand OC, Shelley SL, Williamson TE, Wible JR, Chester SGB, Flynn JJ, Holbrook LT, Lyson TR, Meng J, Miller IM, Püschel HP, Smith T, Spaulding M, Tseng ZJ, Brusatte SL. Brawn before brains in placental mammals after the end-Cretaceous extinction. Science 2022; 376:80-85. [PMID: 35357913 DOI: 10.1126/science.abl5584] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.
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Affiliation(s)
- Ornella C Bertrand
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK
| | - Sarah L Shelley
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK.,Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | | | - John R Wible
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | - Stephen G B Chester
- Department of Anthropology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Department of Anthropology, The Graduate Center, City University of New York, New York, NY, USA.,New York Consortium in Evolutionary Primatology, New York, NY, USA
| | - John J Flynn
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.,Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA.,Ecology, Evolutionary Biology, and Behavior subprogram, PhD Program in Biology, The Graduate Center, City University of New York, New York, NY, USA.,PhD Program in Earth and Environmental Sciences, The Graduate Center, City University of New York, New York, NY, USA
| | - Luke T Holbrook
- Department of Biological Sciences, Rowan University, Glassboro, NJ, USA
| | | | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Ian M Miller
- Denver Museum of Nature & Science, Denver, CO, USA.,National Geographic Society, Washington, DC, USA
| | - Hans P Püschel
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK
| | - Thierry Smith
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Michelle Spaulding
- Department of Biological Sciences, Purdue University Northwest, Westville, IN, USA
| | - Z Jack Tseng
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK.,New Mexico Museum of Natural History and Science, Albuquerque, NM, USA
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5
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Ho CLA, Fichtel C, Huber D. The gray mouse lemur (Microcebus murinus) as a model for early primate brain evolution. Curr Opin Neurobiol 2021; 71:92-99. [PMID: 34768148 DOI: 10.1016/j.conb.2021.09.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/16/2021] [Indexed: 12/23/2022]
Abstract
The gray mouse lemur (Microcebus murinus), one of the world's smallest primates, is thought to share a similar ecological niche and many anatomical traits with early euprimates. As a result, it has been considered a suitable model system for early primate physiology and behavior. Moreover, recent studies have demonstrated that mouse lemurs have comparable cognitive abilities and cortical functional organization as haplorhines. Finally, the small brain size of mouse lemurs provides us with actual lower limits for miniaturization of functional brain circuits within the primate clade. Considering its phylogenetic position and early primate-like traits, the mouse lemurs are a perfect model species to study the early evolution of primate brains.
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Affiliation(s)
- Chun Lum Andy Ho
- University of Geneva, Department of Basic Neurosciences, Rue Michel Servet 1, 1206 Geneva, Switzerland
| | - Claudia Fichtel
- Verhaltensökologie und Soziobiologie, Deutsches Primatenzentrum, Kellnerweg 4, 37077 Göttingen, Germany; Leibniz Science Campus 'Primate Cognition', 37077 Göttingen, Germany
| | - Daniel Huber
- University of Geneva, Department of Basic Neurosciences, Rue Michel Servet 1, 1206 Geneva, Switzerland.
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6
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Pfau D, Jordan CL, Breedlove SM. The De-Scent of Sexuality: Did Loss of a Pheromone Signaling Protein Permit the Evolution of Same-Sex Sexual Behavior in Primates? ARCHIVES OF SEXUAL BEHAVIOR 2021; 50:2267-2276. [PMID: 31016493 DOI: 10.1007/s10508-018-1377-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 12/12/2018] [Accepted: 12/13/2018] [Indexed: 05/15/2023]
Abstract
Primate same-sex sexual behavior (SSSB) is rarely observed in strepsirrhine species, and only somewhat more common in platyrrhines, but is observed in nearly all catarrhine species, including humans, suggesting the common catarrhine ancestor as the origin of routine SSSB. In mice, disruption of the transient receptor potential cation channel 2 (TRPC2) gene, which is crucial for transducing chemosensory signals from pheromones in the vomeronasal organ, greatly increased the likelihood of SSSB. We note that catarrhine primates share a common deleterious mutation in this gene, indicating that the protein was dysfunctional in the common catarrhine ancestral primate approximately 25 mya (million years ago). We hypothesize that the loss of this protein for processing pheromonal signals in males and females made SSSB more likely in a primate ancestral species by effectively lifting a pheromonally mediated barrier to SSSB and that this was an important precursor to the evolution of such behavior in humans. Additional comparisons between SSSB and the functional status of the TRPC2 gene or related proteins across primate species could lend support to or falsify this hypothesis. Our current research indicates that loss of TRPC2 function in developing mice leads to the loss or attenuation of sexually dimorphisms in the adult brain, which may help us to understand the biological underpinnings of SSSB. Our hypothesis offers an ultimate evolutionary explanation for SSSB in humans.
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Affiliation(s)
- Daniel Pfau
- Neuroscience Program, Michigan State University, Giltner Hall, 293 Farm Lane, Room 108, East Lansing, MI, 48824-1101, USA.
| | - Cynthia L Jordan
- Neuroscience Program, Michigan State University, Giltner Hall, 293 Farm Lane, Room 108, East Lansing, MI, 48824-1101, USA
| | - S Marc Breedlove
- Neuroscience Program, Michigan State University, Giltner Hall, 293 Farm Lane, Room 108, East Lansing, MI, 48824-1101, USA
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7
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Kirk EC, Lundeen IK. New observations of the nasal fossa and interorbital region of Shoshonius cooperi based on microcomputerized tomography. J Hum Evol 2020. [DOI: 10.1016/j.jhevol.2020.102748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Smith TD, Craven BA, Engel SM, Bonar CJ, DeLeon VB. Nasal airflow in the pygmy slow loris ( Nycticebus pygmaeus) based on a combined histological, computed tomographic and computational fluid dynamics methodology. ACTA ACUST UNITED AC 2019; 222:jeb.207605. [PMID: 31712355 DOI: 10.1242/jeb.207605] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 11/05/2019] [Indexed: 01/23/2023]
Abstract
'Macrosmatic' mammals have dedicated olfactory regions within their nasal cavity and segregated airstreams for olfaction and respiratory air-conditioning. Here, we examined the 3D distribution of olfactory surface area (SA) and nasal airflow patterns in the pygmy slow loris (Nycticebus pygmaeus), a primate with primitive nasal cavities, except for enlarged eyes that converge upon the posterodorsal nasal region. Using the head of an adult loris cadaver, we co-registered micro-computed tomography (CT) slices and histology sections to create a 3D reconstruction of the olfactory mucosa distribution. Histological sections were used to measure olfactory surface area and to annotate CT reconstructions. The loris has a complex olfactory recess (∼19% of total nasal SA) with multiple olfactory turbinals. However, the first ethmoturbinal has a rostral projection that extends far anterior to the olfactory recess, lined by ∼90% non-olfactory epithelium. Only one (of three) frontoturbinals bears olfactory mucosa. Computational fluid dynamics simulations of nasal airflow and odorant deposition revealed that there is some segregation of respiratory and olfactory flow in the loris nose, but that it is not as distinct as in well-studied 'macrosmats' (e.g. the dog). In the loris, airflow is segregated medially and laterally to vertically elongated, plate-like first ethmoturbinals. Thus, lorises may be said to have certain macrosmatic anatomical characteristics (e.g. olfactory recess), but not segregated nasal airflow patterns that are optimized for olfaction, as in canids. These results imply that a binary 'microsmatic/macrosmatic' dichotomy does not exist. Rather, mammals appear to exhibit complex trends with respect to specialization of the turbinals and recesses.
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Affiliation(s)
- Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, PA 16057, USA
| | - Brent A Craven
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Serena M Engel
- School of Physical Therapy, Slippery Rock University, Slippery Rock, PA 16057, USA
| | | | - Valerie B DeLeon
- Department of Anthropology, University of Florida, Gainesville, FL 32611, USA
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9
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Lundeen IK, Kirk EC. Internal nasal morphology of the Eocene primate Rooneyia viejaensis and extant Euarchonta: Using μCT scan data to understand and infer patterns of nasal fossa evolution in primates. J Hum Evol 2019; 132:137-173. [PMID: 31203844 DOI: 10.1016/j.jhevol.2019.04.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 04/19/2019] [Accepted: 04/19/2019] [Indexed: 11/18/2022]
Abstract
Primates have historically been viewed as having a diminished sense of smell compared to other mammals. In haplorhines, olfactory reduction has been inferred partly based on the complexity of the bony turbinals within the nasal cavity. Some turbinals are covered in olfactory epithelium, which contains olfactory receptor neurons that detect odorants. Accordingly, turbinal number and complexity has been used as a rough anatomical proxy for the relative importance of olfactory cues for an animal's behavioral ecology. Unfortunately, turbinals are delicate and rarely preserved in fossil specimens, limiting opportunities to make direct observations of the olfactory periphery in extinct primates. Here we describe the turbinal morphology of Rooneyia viejaensis, a late middle Eocene primate of uncertain phylogenetic affinities from the Tornillo Basin of West Texas. This species is currently the oldest fossil primate for which turbinals are preserved with minimal damage or distortion. Microcomputed tomography (μCT) reveals that Rooneyia possessed 1 nasoturbinal, 4 bullar ethmoturbinals, 1 frontoturbinal, 1 interturbinal, and an olfactory recess. This pattern is broadly similar to the condition seen in some extant strepsirrhine primates but differs substantially from the condition seen in extant haplorhines. Crown haplorhines possess only two ethmoturbinals and lack frontoturbinals, interturbinals, and an olfactory recess. Additionally, crown anthropoids have ethmoturbinals that are non-bullar. These observations reinforce the conclusion that Rooneyia is not a stem tarsiiform or stem anthropoid. However, estimated olfactory turbinal surface area in Rooneyia is greater than that of similar-sized haplorhines but smaller than that of similar-sized lemuriforms and lorisiforms. This finding suggests that although Rooneyia was broadly plesiomorphic in retaining a large complement of olfactory turbinals as in living strepsirrhines, Rooneyia may have evolved somewhat diminished olfactory abilities as in living haplorhines.
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Affiliation(s)
- Ingrid K Lundeen
- Department of Anthropology, University of Texas at Austin, SAC 4.102, 2201 Speedway Stop C3200, Austin, TX 78712, USA.
| | - E Christopher Kirk
- Department of Anthropology, University of Texas at Austin, SAC 4.102, 2201 Speedway Stop C3200, Austin, TX 78712, USA; Jackson School Museum of Earth History, University of Texas at Austin, J. J. Pickle Research Campus, 10100 Burnet Road, PRC 6-VPL, R7600, Austin, TX 78758, USA
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10
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Saraf MP, Balaram P, Pifferi F, Gămănuţ R, Kennedy H, Kaas JH. Architectonic features and relative locations of primary sensory and related areas of neocortex in mouse lemurs. J Comp Neurol 2018; 527:625-639. [PMID: 29484648 DOI: 10.1002/cne.24419] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/08/2018] [Accepted: 02/08/2018] [Indexed: 12/27/2022]
Abstract
Mouse lemurs are the smallest of the living primates, and are members of the understudied radiation of strepsirrhine lemurs of Madagascar. They are thought to closely resemble the ancestral primates that gave rise to present day primates. Here we have used multiple histological and immunochemical methods to identify and characterize sensory areas of neocortex in four brains of adult lemurs obtained from a licensed breeding colony. We describe the laminar features for the primary visual area (V1), the secondary visual area (V2), the middle temporal visual area (MT) and area prostriata, somatosensory areas S1(3b), 3a, and area 1, the primary motor cortex (M1), and the primary auditory cortex (A1). V1 has "blobs" with "nonblob" surrounds, providing further evidence that this type of modular organization might have evolved early in the primate lineage to be retained in all extant primates. The laminar organization of V1 further supports the view that sublayers of layer 3 of primates have been commonly misidentified as sublayers of layer 4. S1 (area 3b) is proportionately wider than the elongated area observed in anthropoid primates, and has disruptions that may distinguish representations of the hand, face, teeth, and tongue. Primary auditory cortex is located in the upper temporal cortex and may include a rostral area, R, in addition to A1. The resulting architectonic maps of cortical areas in mouse lemurs can usefully guide future studies of cortical connectivity and function.
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Affiliation(s)
- Mansi P Saraf
- Department of Psychology, Vanderbilt University, Nashville, TN, 37240
| | - Pooja Balaram
- Department of Psychology, Vanderbilt University, Nashville, TN, 37240.,MECADEV UMR 7179, Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Brunoy, 91800, France
| | - Fabien Pifferi
- Université de Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, 69500, France
| | - Răzvan Gămănuţ
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Science (CAS) Key Laboratory of Primate Neurobiology, CAS, Shanghai, 200031, China
| | - Henry Kennedy
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Science (CAS) Key Laboratory of Primate Neurobiology, CAS, Shanghai, 200031, China
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN, 37240
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11
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Rossie JB, Smith TD, Beard KC, Godinot M, Rowe TB. Nasolacrimal anatomy and haplorhine origins. J Hum Evol 2017; 114:176-183. [PMID: 29447758 DOI: 10.1016/j.jhevol.2017.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 11/29/2022]
Abstract
Computed tomography X-ray imaging of the internal face in well-preserved primate fossil crania permits reconstruction of the nature of their nasal anatomy, including some soft-tissue features. These features are diagnostic of the primate suborder Haplorhini, and allow reevaluation of the phylogenetic status of several purported early members of the group. Here we examine the nasolacrimal morphology of a broad sample of extant primates, as well as a number of Paleogene fossils. The extant sample confirms the distinctiveness of the two suborders. Of the fossils studied, only Shoshonius cooperi from the late-early Eocene exhibits evidence of a haplorhine nose. This suggests that the haplorhine oronasal complex may have evolved before the postorbital septum, and strengthens the claim that Shoshonius is a close relative of tarsiers and anthropoids. These results indicate that Omomyiformes is not a monophyletic group, and that few of its members possessed the derived oronasal morphology that characterizes crown haplorhines.
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Affiliation(s)
- James B Rossie
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA.
| | - Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, PA 16057, USA; Department of Anthropology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - K Christopher Beard
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA; Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA
| | - Marc Godinot
- Ecole Pratique des Hautes Etudes, PSL, Sorbonne Universités - CR2P - MNHN, CNRS, UPMC - Paris 6, Muséum National d'Histoire Naturelle, Paris, France
| | - Timothy B Rowe
- Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, USA
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12
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13
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Abstract
AbstractX-ray computed tomography (CT) provides a nondestructive means of studying the inside and outside of objects. It allows accurate visualization and measurement of internal features, that are otherwise impossible to obtain nondestructively, and is a lasting digital record that can be made available to future researchers, museums, and the general public. Here, an overview of CT scanning methodologies and protocol is provided, as well as some recent examples of how this technology is allowing paleontologists to make new inroads into understanding the ecology, evolution, and development of both extant and extinct organisms. Lastly, some frontiers and outstanding questions in the acquisition, processing, and storage of digital 3-D morphological data are highlighted.
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14
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Bertrand OC, Amador‐Mughal F, Silcox MT. Virtual endocast of the early Oligocene Cedromus wilsoni (Cedromurinae) and brain evolution in squirrels. J Anat 2017; 230:128-151. [PMID: 27580644 PMCID: PMC5192888 DOI: 10.1111/joa.12537] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2016] [Indexed: 01/21/2023] Open
Abstract
Extant squirrels exhibit extensive variation in brain size and shape, but published endocranial data for living squirrels are limited, and no study has ever examined brain evolution in Sciuridae from the perspective of the fossil record to understand how this diversity emerged. We describe the first virtual endocast for a fossil sciurid, Cedromus wilsoni, which is known from a complete cranium from Wyoming (Orellan, Oligocene), and make comparisons to a diverse sample of virtual endocasts for living sciurids (N = 20). The virtual endocasts were obtained from high-resolution X-ray micro-computed tomography data. Comparisons were also made with endocasts of extinct ischyromyid rodents, the most primitive rodents known from an endocranial record, which provide the opportunity to study the neuroanatomical changes occurring near the base of Sciuridae. The encephalization quotient of C. wilsoni is higher than that of Ischyromys typus from the same epoch, and falls within the range of modern terrestrial squirrel variation, but below the range of extant scansorial, arboreal and gliding sciurids when using cheek-tooth area for the estimation of body mass. In a principal components analysis, the shape of the endocast of C. wilsoni is found to be intermediate between that of primitive fossil taxa and the modern sample. Cedromus wilsoni has a more expanded neocortical surface area, especially the caudal region of the cerebrum, compared with ischyromyid rodents. Furthermore, C. wilsoni had proportionally larger paraflocculi and a more complex cerebellar morphology compared with ischyromyid rodents. These neurological differences may be associated with improvements in vision, although it is worth noting that the size of the parts of the brain most directly involved with vision [the rostral (superior) colliculi and the primary visual cortex] cannot be directly assessed on endocasts. The changes observed could also relate to balance and limb coordination. Ultimately, the available evidence suggests that early squirrels were more agile and visually oriented animals compared with more primitive rodents, which may relate to the process of becoming arboreal. Extant sciurids have an even more expanded neocortical surface area, while exhibiting proportionally smaller paraflocculi, compared with C. wilsoni. This suggests that the neocortex may continue increasing in size in more recent sciurid rodents in relation to other factors than arboreality. Despite the fact that both Primates and Rodentia exhibit neocortical expansion through time, since the adoption of arboreality preceded major increases in the neocortex in Primates, those neurological changes may be related to different ecological factors, underlining the complexity of the inter-relationship between time and ecology in shaping the brain in even closely related clades.
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Affiliation(s)
- Ornella C. Bertrand
- Department of AnthropologyUniversity of Toronto ScarboroughTorontoOntarioCanada
| | | | - Mary T. Silcox
- Department of AnthropologyUniversity of Toronto ScarboroughTorontoOntarioCanada
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15
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Tomiya S, Tseng ZJ. Whence the beardogs? Reappraisal of the Middle to Late Eocene ' Miacis' from Texas, USA, and the origin of Amphicyonidae (Mammalia, Carnivora). ROYAL SOCIETY OPEN SCIENCE 2016; 3:160518. [PMID: 27853569 PMCID: PMC5098994 DOI: 10.1098/rsos.160518] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/09/2016] [Indexed: 05/24/2023]
Abstract
The Middle to Late Eocene sediments of Texas have yielded a wealth of fossil material that offers a rare window on a diverse and highly endemic mammalian fauna from that time in the southern part of North America. These faunal data are particularly significant because the narrative of mammalian evolution in the Paleogene of North America has traditionally been dominated by taxa that are known from higher latitudes, primarily in the Rocky Mountain and northern Great Plains regions. Here we report on the affinities of two peculiar carnivoraforms from the Chambers Tuff of Trans-Pecos, Texas, that were first described 30 years ago as Miacis cognitus and M. australis. Re-examination of previously described specimens and their inclusion in a cladistic analysis revealed the two taxa to be diminutive basal amphicyonids; as such, they are assigned to new genera Gustafsonia and Angelarctocyon, respectively. These two taxa fill in some of the morphological gaps between the earliest-known amphicyonid genus, Daphoenus, and other Middle-Eocene carnivoraforms, and lend additional support for a basal caniform position of the beardogs outside the Canoidea. The amphicyonid lineage had evidently given rise to at least five rather distinct forms by the end of the Middle Eocene. Their precise geographical origin remains uncertain, but it is plausible that southern North America served as an important stage for a very early phase of amphicyonid radiation.
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Affiliation(s)
- Susumu Tomiya
- Integrative Research and Ganz Family Collections Centers, Field Museum of Natural History, Chicago, IL 60605, USA
- University of California Museum of Paleontology, Berkeley, CA 94720, USA
| | - Zhijie Jack Tseng
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, USA
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16
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Harrington AR, Silcox MT, Yapuncich GS, Boyer DM, Bloch JI. First virtual endocasts of adapiform primates. J Hum Evol 2016; 99:52-78. [DOI: 10.1016/j.jhevol.2016.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 06/06/2016] [Accepted: 06/30/2016] [Indexed: 12/23/2022]
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17
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Balanoff AM, Bever GS, Colbert MW, Clarke JA, Field DJ, Gignac PM, Ksepka DT, Ridgely RC, Smith NA, Torres CR, Walsh S, Witmer LM. Best practices for digitally constructing endocranial casts: examples from birds and their dinosaurian relatives. J Anat 2016; 229:173-90. [PMID: 26403623 PMCID: PMC4948053 DOI: 10.1111/joa.12378] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2015] [Indexed: 11/28/2022] Open
Abstract
The rapidly expanding interest in, and availability of, digital tomography data to visualize casts of the vertebrate endocranial cavity housing the brain (endocasts) presents new opportunities and challenges to the field of comparative neuroanatomy. The opportunities are many, ranging from the relatively rapid acquisition of data to the unprecedented ability to integrate critically important fossil taxa. The challenges consist of navigating the logistical barriers that often separate a researcher from high-quality data and minimizing the amount of non-biological variation expressed in endocasts - variation that may confound meaningful and synthetic results. Our purpose here is to outline preferred approaches for acquiring digital tomographic data, converting those data to an endocast, and making those endocasts as meaningful as possible when considered in a comparative context. This review is intended to benefit those just getting started in the field but also serves to initiate further discussion between active endocast researchers regarding the best practices for advancing the discipline. Congruent with the theme of this volume, we draw our examples from birds and the highly encephalized non-avian dinosaurs that comprise closely related outgroups along their phylogenetic stem lineage.
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Affiliation(s)
- Amy M. Balanoff
- Department of Anatomical SciencesStony Brook UniversityStony BrookNYUSA
| | - G. S. Bever
- Department of AnatomyNew York Institute of TechnologyCollege of Osteopathic MedicineOld WestburyNYUSA
| | - Matthew W. Colbert
- Department of Geological SciencesThe University of Texas at AustinAustinTXUSA
| | - Julia A. Clarke
- Department of Geological SciencesThe University of Texas at AustinAustinTXUSA
| | - Daniel J. Field
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
| | - Paul M. Gignac
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOKUSA
| | | | - Ryan C. Ridgely
- Department of Biomedical SciencesHeritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
| | - N. Adam Smith
- Department of Earth SciencesThe Field Museum of Natural HistoryChicagoILUSA
| | | | - Stig Walsh
- Department of Natural SciencesNational Museums ScotlandEdinburghUK
| | - Lawrence M. Witmer
- Department of Biomedical SciencesHeritage College of Osteopathic MedicineOhio UniversityAthensOHUSA
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18
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X-ray computed tomography datasets for forensic analysis of vertebrate fossils. Sci Data 2016; 3:160040. [PMID: 27272251 PMCID: PMC4896130 DOI: 10.1038/sdata.2016.40] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/28/2016] [Indexed: 11/09/2022] Open
Abstract
We describe X-ray computed tomography (CT) datasets from three specimens recovered from Early Cretaceous lakebeds of China that illustrate the forensic interpretation of CT imagery for paleontology. Fossil vertebrates from thinly bedded sediments often shatter upon discovery and are commonly repaired as amalgamated mosaics grouted to a solid backing slab of rock or plaster. Such methods are prone to inadvertent error and willful forgery, and once required potentially destructive methods to identify mistakes in reconstruction. CT is an efficient, nondestructive alternative that can disclose many clues about how a specimen was handled and repaired. These annotated datasets illustrate the power of CT in documenting specimen integrity and are intended as a reference in applying CT more broadly to evaluating the authenticity of comparable fossils.
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19
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Mota B, Herculano-Houzel S. Response to Comments on "Cortical folding scales universally with surface area and thickness, not number of neurons". Science 2016; 351:826. [PMID: 26912888 DOI: 10.1126/science.aad2346] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
De Lussanet claims that our model that accounts for the degree of folding of the cerebral cortex based on the product of cortical surface area and the square root of cortical thickness is better reduced to the product of gray-matter proportion and folding index. Lewitus et al., in turn, claim that the assumptions of our model are in conflict with experimental data; that the model does not accurately fit the data; and that the ancestral mammalian brain was gyrencephalic. Here, we show that both claims are inappropriate.
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Affiliation(s)
- Bruno Mota
- Instituto de Física, Universidade Federal do Rio de Janeiro, Brasil
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20
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Ramdarshan A, Orliac MJ. Endocranial morphology ofMicrochoerus erinaceus(Euprimates, Tarsiiformes) and early evolution of the Euprimates brain. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:5-16. [DOI: 10.1002/ajpa.22868] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 08/31/2015] [Accepted: 09/02/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Anusha Ramdarshan
- Paleontology division, Institut des Sciences de l'Evolution, UMR 5554 CNRS, IRD, EPHE; Université De Montpellier; 34095 Montpellier Cedex 5 France
| | - Maeva J. Orliac
- Paleontology division, Institut des Sciences de l'Evolution, UMR 5554 CNRS, IRD, EPHE; Université De Montpellier; 34095 Montpellier Cedex 5 France
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21
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Heritage S. Modeling olfactory bulb evolution through primate phylogeny. PLoS One 2014; 9:e113904. [PMID: 25426851 PMCID: PMC4245229 DOI: 10.1371/journal.pone.0113904] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Accepted: 11/02/2014] [Indexed: 11/23/2022] Open
Abstract
Adaptive characterizations of primates have usually included a reduction in olfactory sensitivity. However, this inference of derivation and directionality assumes an ancestral state of olfaction, usually by comparison to a group of extant non-primate mammals. Thus, the accuracy of the inference depends on the assumed ancestral state. Here I present a phylogenetic model of continuous trait evolution that reconstructs olfactory bulb volumes for ancestral nodes of primates and mammal outgroups. Parent-daughter comparisons suggest that, relative to the ancestral euarchontan, the crown-primate node is plesiomorphic and that derived reduction in olfactory sensitivity is an attribute of the haplorhine lineage. The model also suggests a derived increase in olfactory sensitivity at the strepsirrhine node. This oppositional diversification of the strepsirrhine and haplorhine lineages from an intermediate and non-derived ancestor is inconsistent with a characterization of graded reduction through primate evolution.
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Affiliation(s)
- Steven Heritage
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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