{{Short description|Extinct family of primates}} {{For|an explanation of very similar terms|Tarsiiformes}} {{Automatic taxobox | fossil_range = {{Fossil range|56|34|latest=0}} Late Paleocene – Oligocene<ref name=MamEv>{{cite book|author= Savage, RJG, & Long, MR|year= 1986|title= Mammal Evolution: an illustrated guide|publisher= Facts on File|location= New York|pages= 365|isbn= 978-0-8160-1194-0|url= https://archive.org/details/mammalevolutioni0000sava|url-access= registration}}</ref> <br> Possible descendant taxon Tarsiidae survives to present | image = Necrolemur.JPG | image_caption = The skull of ''Necrolemur'' | display_parents = 2 | taxon = Omomyidae | authority = Trouessart, 1879 | subdivision_ranks = Subgroups | subdivision = *†Anaptomorphinae *†Microchoerinae *†Omomyinae *†Tarkadectinae *Tarsiidae (cladistically included<ref>{{Cite journal|last1=Morse|first1=Paul E.|last2=Chester|first2=Stephen G. B.|last3=Boyer|first3=Doug M.|last4=Smith|first4=Thierry|last5=Smith|first5=Richard|last6=Gigase|first6=Paul|last7=Bloch|first7=Jonathan I.|date=2019-03-01|title=New fossils, systematics, and biogeography of the oldest known crown primate Teilhardina from the earliest Eocene of Asia, Europe, and North America|url=http://www.sciencedirect.com/science/article/pii/S0047248417303585|journal=Journal of Human Evolution|language=en|volume=128|pages=103–131|doi=10.1016/j.jhevol.2018.08.005|pmid=30497682|bibcode=2019JHumE.128..103M |s2cid=54167483|issn=0047-2484|url-access=subscription}}</ref>) | synonyms = Tarsiiformes }}
'''Omomyidae''' is a group of early primates that radiated during the Eocene epoch between about {{Ma|55|34|million years ago}} (mya). Fossil omomyids are found in North America, Europe & Asia, making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids (family Adapidae). Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene (56 mya) in North America, Europe, and Asia, and are the earliest known crown primates.
Omomyids are generally as regarded as closely related to or within the Tarsiiformes, and thus most closely related to tarsiers among living primates.<ref>{{Cite journal |last1=Salford~d.devries@salford.ac.uk |first1=Dorien de Vries~University of |last2=Salford~r.m.d.beck@salford.ac.uk |first2=Robin M. D. Beck~University of |date=2023-03-26 |title=Twenty-five well-justified fossil calibrations for primate divergences |url=https://palaeo-electronica.org/content/2023/3777-primate-fossil-calibrat |access-date=2025-09-19 |journal=Palaeontologia Electronica |doi=10.26879/1249 |language=en|doi-access=free }}</ref>
==Characteristics== [[File:TeilhardinaDB15.jpg|left|thumb|253x253px|Life restoration of ''Teilhardina'']] [[File:Necrolemur NT.jpg|left|thumb|Life restoration of ''Necrolemur'']] Features that characterize many omomyids include large orbits (eye sockets), shortened rostra and dental arcades, loss of anterior premolars, cheek teeth adapted for insectivorous or frugivorous diets, and relatively small body mass (i.e., less than 500 g). However, by the late middle Eocene (about 40 mya), some North American omomyids evolved body masses in excess of {{cvt|1|kg|lb}} and frugivorous or folivorous diets. The largest omomyids were ''Macrotarsius'' and ''Ourayia'', both at {{cvt|1.5|-|2|kg|lb}} in weight.<ref name=Dunn2010>Rachel H. Dunn. "[https://www.sciencedirect.com/science/article/abs/pii/S0047248410000382 Additional postcranial remains of omomyid primates from the Uinta Formation, Utah and implications for the locomotor behavior of large-bodied omomyids]". Journal of Human Evolution Volume 58, Issue 5, May 2010, pp. 406-417</ref> Large orbits in genera such as ''Tetonius'', ''Shoshonius'', ''Necrolemur'', and ''Microchoerus'' indicate that these taxa were probably nocturnal. At least one omomyid genus from the late Eocene of Texas (''Rooneyia'') had small orbits and was probably diurnal.
Like primates alive today, omomyids had grasping hands and feet with digits tipped by nails instead of claws, although they possessed toilet claws like modern lemurs.<ref>{{cite web| title=Early Primates Groomed with Claws|url=https://blogs.scientificamerican.com/laelaps/early-primates-groomed-with-claws/}}</ref> Features of their skeletons strongly indicate that omomyids lived in trees.<ref name=Dunn2010/> In at least one genus (''Necrolemur''), the lower leg bones, the tibia and fibula, were fused as in modern tarsiers. This feature may indicate that ''Necrolemur'' leaped frequently. Most other omomyid genera (e.g., ''Omomys'') lack specializations for leaping, and their skeletons are more like those of living dwarf and mouse lemurs.
Omomyid systematics and evolutionary relationships are controversial. Authors have suggested that omomyids are either: #stem haplorhines [i.e., basal members of the group including living tarsiers and anthropoids].<ref>{{cite journal |title=Anthropoid origins |year=1997 |last1=Kay |first1=Richard F. |last2=Ross |first2=Callum |last3=Williams |first3=Blythe A. |journal=Science |volume=275 |issue=5301 |pages=797–804 |pmid=9012340 |s2cid=220087294 |doi=10.1126/science.275.5301.797}}</ref> #stem tarsiiformes [i.e., basal offshoots of the tarsier lineage].<ref>{{cite journal |first=Frederick |last=Szalay |title=Systematics of the Omomyidae (Tarsiiformes, Primates): Taxonomy, phylogeny, and adaptations |year=1976 |journal=Bulletin of the American Museum of Natural History |volume=156 |issue=3 |pages=157–450}}</ref> #stem primates more closely related to adapids than to living primate taxa.
Recent research suggests the Omomyiformes are stem haplorhines, making them likely a paraphyletic grouping.<ref>{{Cite journal|last1=Rossie|first1=James B.|last2=Smith|first2=Timothy D.|last3=Beard|first3=K. Christopher|last4=Godinot|first4=Marc|last5=Rowe|first5=Timothy B.|date=2018|title=Nasolacrimal anatomy and haplorhine origins|journal=Journal of Human Evolution|volume=114|pages=176–183|doi=10.1016/j.jhevol.2017.11.004|pmid=29447758|bibcode=2018JHumE.114..176R |issn=0047-2484|doi-access=free}}</ref>
Attempts to link omomyids to living groups have been complicated by their primitive (plesiomorphic) skeletal anatomy. For example, omomyids lack the numerous skeletal specializations of living haplorhines. These haplorhine adaptations - absent in omomyids - include: # significant reduction of the canal for the stapedial branch of the internal carotid artery. # route of the canal to house the promontory branch of the internal carotid artery through the auditory bulla of the temporal bone, i.e. "perbullar" (rather than across the promontory of tympanic cavity, "transpromontorial") . # contact between the alisphenoid and zygomatic bones. # presence of an anterior accessory cavity confluent with the tympanic cavity.
Omomyids further demonstrate a gap between the upper central incisors, which presumably indicates the presence of a rhinarium and philtrum to channel fluids into the vomeronasal organ. Omomyids as a group also lack most of the derived specializations of living tarsiers, such as extremely enlarged orbits (''Shoshonius'' is a possible exception), a large supra-meatal foramen for an anastomosis between the posterior auricular and middle meningeal circulation (again, ''Shoshonius'' is a possible exception, but the contents of the foramen in this extinct taxon are unknown), and extreme postcranial adaptations for leaping.
Among primates, omomyids have a uniquely derived characteristic. This is the presence of an aphaneric (not visible or readily distinguishable, due to its position), or "intrabullar" (within the bullae), ectotympanic bone, connected to the lateral wall of the auditory bulla by an unbroken annular bridge.
==Classification== The exact taxonomy of Omomyidae is contested, as many authors question if Omomyidae represents a real monophyletic group. These authors propose that "Omomyidae" should be split into 2 groups, Tarsiidae (including living tarsiers) for more derived large-eyed members and Anaptomorphidae for more basal small-eyed members.<ref>{{Cite journal |last=Rosenberger |first=Alfred L. |date=May 2011 |title=The Face of Strigorhysis : Implications of Another Tarsier-like, Large-Eyed Eocene North American Tarsiiform Primate |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.21367 |journal=The Anatomical Record |language=en |volume=294 |issue=5 |pages=797–812 |doi=10.1002/ar.21367 |pmid=21433304 |issn=1932-8486|url-access=subscription }}</ref> Despite this, Omomyidae is still oftentimes used in literature, and the subfamilies are arranged as follows.<ref>{{Cite journal |last=Gingerich |first=Philip D. |date=1981-05-01 |title=Early cenozoic omomyidae and the evolutionary history of tarsiiform primates |url=https://www.sciencedirect.com/science/article/pii/S0047248481800577 |journal=Journal of Human Evolution |volume=10 |issue=4 |pages=345–374 |doi=10.1016/S0047-2484(81)80057-7 |bibcode=1981JHumE..10..345G |issn=0047-2484|url-access=subscription }}</ref> * '''Family Omomyidae''' ** Subfamily Anaptomorphinae ** Subfamily Microchoerinae ** Subfamily Omomyinae Unranked or contested genera within Omomyidae include
* ''Altanius''- Debated to be a basal omomyid or a basal adapid<ref>{{Cite journal |last1=Gingerich |first1=Philip D. |last2=Dashzeveg |first2=Demberelyin |last3=Russell |first3=Donald E. |date=1991-01-01 |title=Dentition and systematic relationships of Altanius orlovi (Mammalia, Primates) from the early Eocene of Mongolia |url=https://dx.doi.org/10.1016/0016-6995%2891%2980029-Y |journal=Geobios |volume=24 |issue=5 |pages=637–646 |doi=10.1016/0016-6995(91)80029-Y |bibcode=1991Geobi..24..637G |issn=0016-6995|url-access=subscription }}</ref> * ''Kohatius''- Unknown placement due to poor material<ref>{{Cite journal |last1=Ni, Xijun |url=https://www.biodiversitylibrary.org/item/281060 |title=Discovery of the first early Cenozoic euprimate (Mammalia) from Inner Mongolia |last2=Ni |first2=Xijun |last3=Beard |first3=K. Christopher |last4=Meng |first4=Jin |last5=Wang |first5=Yuanqing |last6=Gebo |first6=Daniel Lee |date=2007 |journal=American Museum Novitates |issue=3571 |page=1 |doi=10.1206/0003-0082(2007)528[1:DOTFEC]2.0.CO;2 }}</ref>
==References== {{Reflist}}<!--added above External links/Sources by script-assisted edit-->
==External links== *[https://web.archive.org/web/19991023103431/http://www.geocities.com/CapeCanaveral/Lab/8932/Adapidae.html “Adapidae and Omomyidae”] *[https://web.archive.org/web/20050829063256/http://www.fmnh.helsinki.fi/users/haaramo/metazoa/Deuterostoma/Chordata/Synapsida/Eutheria/Primates/Tarsiiformes.htm Mikko's Phylogeny page]
{{Haplorhini|Ha.}} {{Taxonbar|from=Q134979}} {{Authority control}}
Category:Omomyidae Category:Haplorhini Category:Prehistoric primates Category:Eocene primates Category:Oligocene primates Category:Paleocene first appearances Category:Primate families Category:Oligocene extinctions Category:Prehistoric mammal families Category:Paraphyletic groups