View source for Cantius

{{Short description|Extinct genus of primates}}
{{for|the saint|Cantius, Cantianus, and Cantianilla}}
{{Automatic taxobox
| taxon = Cantius
|image = Cantius trigonodus skull mandible.JPG
| authority = Simons, 1962
| fossil_range = {{Fossil range|56.0|47.8}}[[Eocene|Early Eocene]]<ref>{{Cite web|title=PBDB|url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=40754&is_real_user=1|access-date=2021-07-28|website=paleobiodb.org}}</ref>
| subdivision_ranks = Species
| subdivision =
* ''C. abditus'' <small>Gingerich & Simons, 1977</small>
* ''C. angulatus'' <small>Cope, 1875</small>
* ''C. antediluvius'' <small>Kihm, 1992</small>
* ''C. eppsi'' <small>Cooper, 1932</small>
* ''[[Cantius frugivorus|C. frugivorus]]'' <small>Cope, 1875</small>
* ''C. lohseorum'' <small>Robinson, 2016</small>
* ''C. mckennai'' <small>Gingerich & Simons 1977</small>
* ''C. nunienus'' <small>Cope, 1881</small>
* ''C. ralstoni'' <small>Matthew, 1915</small>
* ''C. savagei'' <small>Gingerich, 1977</small>
* ''C. simonsi'' <small>Gunnell, 2002</small>
* ''C. torresi'' <small>Gingerich, 1986</small>
}}
'''''Cantius''''' is a genus of [[adapiform]] [[primate]]s from the early [[Eocene]] of [[North America]] and [[Europe]]. It is extremely well represented in the fossil record in North America and has been hypothesized to be the direct ancestor of ''[[Notharctus]]'' in North America.<ref name=Cantius_1/> The evolution of ''Cantius'' is characterized by a significant increase in body mass that nearly tripled in size. The earliest species were considered small-sized and weighed in around {{cvt|1|kg}}, while the later occurring species were considered medium-sized and likely weighed in around {{cvt|3|kg}}.<ref name=Cantius_1/> Though significantly smaller, the fossil remains discovered of the various species of ''Cantius'' have striking similarities to that of ''Notharctus'' and ''[[Smilodectes]]''.<ref name=Cantius_1/> It is likely ''Cantius'' relied on arboreal quadrupedal locomotion, primarily running and leaping.<ref name=Cantius_1/> This locomotor pattern comparable to that of extant lemurs, which has fostered the hypothesis that ''Cantius'' and other strepsirrhine adapiforms may have a close phylogenetic affinity to living lemurs.<ref name=Cantius_3/>
==Description==
The upper and lower dental formula of ''Cantius'' consisted of two incisors, one canine, four premolars, and three molars.<ref name=Cantius_1/> In the lower molars, it is common to see a trigonid consisting of three cusps as well as a broad-basined talonid.<ref name=Cantius_1/> The upper molars are interesting for North American species of ''Cantius'', as earlier species had simple tritubercular teeth while the later species develop a [[pseudohypocone]] from the [[postprotocingulum]] (also known as the [[nannopithex fold]]).<ref name=Cantius_1/> Given its unfused mandibular symphysis and molar cusp morphology, it has been inferred that ''Cantius'' was likely a frugivore that consumed fruit (as opposed to a folivorous diet of leaves and other plant material).<ref name=Cantius_1/> ''Cantius'' also exhibits canine dimorphism, with males possessing relatively larger canine teeth than females.<ref name=Cantius_2/> Thus ''Cantius'' can be considered a sexually dimorphic species. Specifically, ''C. torresi'' lower canines clearly demonstrate sexual dimorphism in having a male/female [canine] length ratio that falls within the range of an expected dimorphic primate.<ref name=Cantius_2/>
The postcranial skeletal anatomy of ''Cantius'' suggests it was arboreal quadruped capable of running and leaping. This locomotor behavior of ''Cantius'' has been interpreted from its relatively  long ischium and much more distal inferior tibial tuberosity. These features indicate that ''Cantius'' was capable of powerful extension of the thigh and flexion at the knee. These actions were crucial for the locomotor and postural behavior of ''Cantius''.<ref name=Cantius_3/> The orbits of ''Cantius'' have fueled a long-standing debate regarding the activity pattern of the extinct adapiform. After examination of orbital shape and depth, researchers interpreted ''Cantius'' as nocturnal, as its orbital dimensions fall well-above the distribution of extant nocturnal primates.<ref name=Cantius_4/>
==Taxonomy==
There are currently 11 recognized species of ''Cantius'': ''C. abditus'', ''C. angulatus'', ''C. eppsi'', ''C. frugivorous'', ''C. mckennai'', ''C. nunienus'', ''C. ralstoni'', ''C. savagei'', ''C. simonsi'', ''C. torresi'', ''C. trigonodus''.<ref name=Cantius_1/> The earliest of these species (for North American ''Cantius'') is believed to be ''C. torresi'', which has laso been reconstructed as the smallest species within the genus (with ''C. eppsi'' being closest in size).<ref name=Cantius_6/> Thus, considering the gradual pattern of body size increase documented in the ''Cantius'' lineage, ''C. torresi'' is likely to be considerably older than the later species, if not the oldest species. Along with the size comparison, ''C. torresi'' remains were identified within the [[Big Red Sequence]] within the Bighorn Basin PETM chart, thus restricting it to a geologic age older than later ''Cantius'' species.<ref name=Cantius_7/>
==Morphological change and key taxa==
The established age and antiquity of the ''Cantius'' lineage reveals an interesting and well-resolved timeline of adaptation and evolutionary change within [[Notharctidae]]. Noteworthy and well-studied species of ''Cantius'' include ''C. torresi'' and ''C. abditus''. ''C. torresi'', the oldest confirmed species of ''Cantius'', exhibits sexual dimorphism in the canines body size. Thus, it can be inferred that ''Cantius'' (and its descendants) were polygynous.<ref name=Cantius_2/>
After a nearly complete ''C. abditus'' skull was discovered in the [[Early Eocene]] [[Willwood Formation]] of the Bighorn Basin, where many fossils of several species of ''Cantius'' have been found, the geologic age of the fossil was ascertained and a comparative study was conducted.<ref name=Cantius_8/> The study revealed that ''C. abditus'' was roughly 2 million years younger than the older species of ''Cantius'' to which it was compared.<ref name=Cantius_5/> Moreover, the reconstructed body mass of ''C. abditus'' was estimated to be ~3000 grams, which is larger than earlier ''Cantius'' species, and thus conforming to the well-documented pattern of gradual body size increase within the lineage.<ref name=Cantius_1/>
Through comparison of ''C. abditus'', various other species of ''Cantius'', ''Notharctus'', and ''Smilodectes'', researchers were able to identify near identical features in the auditory regions of these species, as well as that of extant lemurs.<ref name=Cantius_8/>
==References==
{{Reflist|refs=
<ref name=Cantius_1>Fleagle, John G. Primate Adaptation and Evolution. 3rd ed. Stony Brook, NY: Elsevier Science, 2013.</ref>
<ref name=Cantius_2>Gingerich, Philip D. "Sexual Dimorphism in Earliest Eocene Cantis Torresi (Mammalia, Primates, Adapoidea)." (1995).</ref>
<ref name=Cantius_3>Rose, Kenneth D., and Alan Walker. “The Skeleton of Early EoceneCantius, Oldest Lemuriform Primate.” American Journal of Physical Anthropology 66, no. 1 (1985): 73–89. https://doi.org/10.1002/ajpa.1330660107.</ref>
<ref name=Cantius_4>Ross, Callum F, Margaret I Hall, and Christopher P Heesy. “Were Basal Primates Nocturnal? Evidence From Eye and Orbit Shape.” Essay. In PRIMATE ORIGINS: Adaptations and Evolution, 233–56. SPRINGER-VERLAG NEW YORK, 2007.</ref>
<ref name=Cantius_5>Kay, Richard F., and E. Christopher Kirk. “Osteological Evidence for the Evolution of Activity Pattern and Visual Acuity in Primates.” American Journal of Physical Anthropology 113, no. 2 (2000): 235–62.</ref>
<ref name=Cantius_6>Gingerich, Philip D. “Early Eocene Cantius Torresi—Oldest Primate of Modern Aspect from North America.” Nature 319, no. 6051 (January 23, 1986): 319–21. https://doi.org/10.1038/319319a0.</ref>
<ref name=Cantius_7>Wing, Scott & Bloch, Jonathan & Bowen, G.J. & Boyer, Doug & Chester, Stephen & Diefendorf, A.F. & Harrington, G.J. & Kraus, Mary & Secord, Ross & McInerney, Francesca. (2009). Coordinated sedimentary and biotic change during the Paleocene-Eocene Thermal Maximum in the Bighorn Basin, Wyoming, USA.” GNS Science Miscellaneous Series. 18. 157-163.</ref>
<ref name=Cantius_8>Rose, K.D., R.D.E. MacPhee, and J.P. Alexander. “Skull of Early Eocene Cantius Abditus (Primates: Adapiformes) and Its Phylogenetic Implications, With a Reevaluation Of ‘Hesperolemur’ Actius.” American Journal of Physical Anthropology 109, no. 4 (1999): 523–39.</ref>
* <!-- {{Sfn|Gebo|2002}} -->{{cite book | last1 = Gebo | first1 = D.L. | contribution = Adapiformes: Phylogeny and adaptation | year = 2002 | editor-last1 = Hartwig | editor-first1 = W.C. | title = The Primate Fossil Record | publisher = [[Cambridge University Press]] | isbn = 978-0-521-08141-2 | oclc = 47254191 | url = https://books.google.com/books?id=Ezm1OA_s6isC&pg=PA21 }}
}}
{{Strepsirrhini|S.}}
{{Taxonbar|from=Q4095196}}
[[Category:Notharctinae]]
[[Category:Eocene primates]]
[[Category:Prehistoric primate genera]]
[[Category:Fossil taxa described in 1962]]
[[Category:Extinct mammals of Europe]]