{{Short description|Extinct subfamily of carnivores}} {{Automatic taxobox | image = Strobodon stirtoni.jpg | image_caption = ''Aelurodon stirtoni'' | name = Borophagines | fossil_range = {{Fossil range|34|2.5}} <small>Oligocene-Earliest Pleistocene</small> | taxon = Borophaginae | authority = Simpson (1945)<ref>{{Cite journal |last=Simpson |first=G.G. |author-link=George Gaylord Simpson |date=1945 |title=The principles of classification and a classification of mammals |journal=Bulletin of the American Museum of Natural History |volume=85 |pages=i–xvi, 1–350 |hdl=2246/1104}}</ref> | subdivision_ranks = Genera | subdivision = See text }}
The extinct '''Borophaginae''' form one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Hesperocyoninae and extant Caninae.<ref>{{cite book|last1=Miklosi|first1=Adam|title=Dog Behaviour, Evolution, and Cognition|publisher=Oxford University Press|edition=2|series=Oxford Biology|year=2015|pages=103–107|url=https://books.google.com/books?id=VT-WBQAAQBAJ&pg=PA103|isbn=978-0199545667}}</ref> Borophaginae, called "bone-crushing dogs",<ref>{{Paleodb|taxon|83323}}</ref><ref>{{fossilworks |id=83323 |title=''Borophaginae'' |access-date=29 August 2018 }}</ref> were endemic to North America during the Oligocene to Pliocene and lived roughly 34–2.5 million years ago, existing for about {{Mya|34-2.5|million years}}.
==Origin== {{Cladogram |align=left|title=Canid subfamilies |cladogram={{clade|style=font-size:85%;line-height:80%;width:264px; |style1=background-color:#ccccff; |label1=Canidae |1={{clade |1={{extinct}}Hesperocyoninae 80 px |2={{clade |1={{extinct}}'''Borophaginae''' <span style="{{MirrorH}}">70 px</span> |2= Caninae 70 px }} }} }} }}
The Borophaginae descended from the subfamily Hesperocyoninae. The earliest and most primitive borophagine is the genus ''Archaeocyon'', which is a small fox-sized animal mostly found in the fossil beds in western North America. The borophagines soon diversified into several major groups. They evolved to become considerably larger than their predecessors, and filled a wide range of niches in late Cenozoic North America, from small omnivores to powerful, bear-sized carnivores, such as ''Epicyon''.<ref name="Wangetal">{{Cite journal |last1=Wang |first1=Xiaoming |last2=Tedford |first2=Richard |last3=Taylor |first3=Beryl |date=1999-11-17 |title= Phylogenetic systematics of the Borophaginae (Carnivora, Canidae) |journal=Bulletin of the American Museum of Natural History |volume=243 |hdl=2246/1588}}</ref>
==Species== [[File:Borophagus secundus (top), Aelurodon taxoides (middle), Tomarctus brevirostris (bottom) (cropped 2).jpg|left|thumb|359x359px|''Borophagus secundus'' (top), ''Aelurodon taxoides'' (middle), ''Tomarctus brevirostris'' (bottom).]] There are 66 identified borophagine species, including 18 newly identified species that range from the Orellan to Blancan ages. A phylogenetic analysis of the species was conducted using cladistic methods, with Hesperocyoninae as an archaic group of canids, as the outgroup. Aside from some transitional forms, Borophaginae can be organized into four major clades: Phlaocyonini, Cynarctina, Aelurodontina, and Borophagina (all erected as new tribes or subtribes). The Borophaginae begins with a group of small fox-sized genera, such as ''Archaeocyon'', ''Oxetocyon'', ''Otarocyon'', and ''Rhizocyon'', in the Orellan through early Arikareean stages.<ref name="Wangetal" /> These canids reached their maximum diversity of species around 28 million years ago.
Often generically referred to as "bone-crushing dogs" for their powerful teeth and jaws, and hyena-like features (although their dentition was more primitive than that of hyenas), their fossils are abundant and widespread; in all likelihood, they were probably one of the top predators of their ecosystems.<ref name="Wangetal" /><ref>{{Cite book |title=Prehistoric Mammals |url=https://archive.org/details/nationalgeograph0000turn |url-access=limited |last=Turner |first=Alan |date=2004 |publisher=National Geographic |isbn=0792271343 |location=Washington, D.C. |pages=[https://archive.org/details/nationalgeograph0000turn/page/112 112]–114 |oclc=54079923}}</ref> Their good fossil record has also allowed a detailed reconstruction of their phylogeny, showing that the group was highly diverse in its heyday.<ref name="Wangetal" /> All Borophaginae had a small fifth toe on their rear feet (similar to the toes that bear dew claws on the front feet), where as all modern Caninae have only four toes normally.<ref>{{Cite book |title=Dogs : their fossil relatives and evolutionary history |last1=Wang |first1=Xiaoming |last2=Tedford |first2=Richard H. |publisher=Columbia University Press |date=2008 |isbn=9780231135283 |location=New York |oclc=185095648 |url= https://books.google.com/books?id=degwyTaHLt8C}}</ref>
Noteworthy genera in this group are ''Aelurodon'', ''Epicyon'', and ''Borophagus'' (=''Osteoborus''). According to Xiaoming Wang, the Borophaginae played broad ecological roles that are performed by at least three living carnivoran families, Canidae (which they were a part of), Hyaenidae, and Procyonidae. thumb|370px|right|Phylogeny of borophagines by R.L. Tedford, 1977 [[File:Canidae Species Divesity.png|thumb|370px|right|Fluctuation of species within Canidae over 40 million years]]
==Classification== Borophagine taxonomy, following Wang et al.<ref name="Wangetal" /> (million years=in existence) *Family Canidae **'''Subfamily †Borophaginae''' ***†''Archaeocyon'' 33—26 Ma, existing {{Mya|33-26|million years}} ***†''Oxetocyon'' 33—28 Ma, existing {{Mya|32-28|million years}} ***†''Otarocyon'' 34—30 Ma, existing {{Mya|34-30|million years}} ***†''Rhizocyon'' 33—26 Ma, existing {{Mya|30-26|million years}} ***Tribe †Phlaocyonini 33—13 Ma, existing {{Mya|33-13|million years}} ****†''Cynarctoides'' 30—18 Ma, existing {{Mya|30-18|million years}} ****†''Phlaocyon'' 30—19 Ma,{{Mya|30-19|million years}} ***Tribe †Borophagini 30—3 Ma, existing {{Mya|30-3|million years}} ****†''Cormocyon'' 30—20 Ma, existing {{Mya|30-20|million years}} ****†''Desmocyon'' 25—16 Ma, existing {{Mya|25-16|million years}} ****†''Metatomarctus'' 19—16 Ma, existing {{Mya|19-16|million years}} ****†''Euoplocyon'' 18—16 Ma, existing {{Mya|18-16|million years}} ****†''Psalidocyon'' 16—13 Ma, existing {{Mya|20.6-13.6|million years}} ****†''Microtomarctus'' 21—13 Ma, existing {{Mya|20.6-13.6|million years}} ****†''Protomarctus'' 20—16 Ma, existing {{Mya|20-16|million years}} ****†''Tephrocyon'' 16—14 Ma, existing {{Mya|16.3-13.6|million years}} ****Subtribe †Cynarctina 20—10 Ma, existing {{Mya|20-10|million years}} *****†''Paracynarctus'' 19—16 Ma, existing {{Mya|19-16|million years}} *****†''Cynarctus'' 16—12 Ma, existing {{Mya|16-12|million years}} ****Subtribe †Aelurodontina 20—5 Ma, existing {{Mya|20-5|million years}} *****†''Tomarctus'' 23—16 Ma, existing {{Mya|23-16|million years}} *****†''Aelurodon'' 16—12 Ma, existing {{Mya|16-12|million years}} ****Subtribe †Borophagina *****†''Paratomarctus'' 16—5 Ma, existing {{Mya|16.3-5.3|million years}} *****†''Carpocyon'' 16—5 Ma, existing {{Mya|16-5|million years}} *****†''Protepicyon'' 16—12 Ma, existing {{Mya|16.3-13.6|million years}} *****†''Epicyon'' 12—10 Ma, existing {{Mya|12-10|million years}} *****†''Borophagus'' (=''Osteoborus'') 12—5 Ma, existing {{Mya|12-5|million years}}
Cladogram showing borophagine interrelationships, following Wang et al., figure 141:<ref name="Wangetal" />
{{Clade | style=font-size:75%;line-height:75% | label1=Canidae | 1={{Clade | 1=Hesperocyoninae | 2={{Clade | 1=Caninae | label2=Borophaginae | 2={{Clade | 1=''Archaeocyon'' <!-- clade in Fig 141, trichomy in Figs 139 and 140--> | 2=''Oxetocyon'' <!--Oxetocyon and Otarocyon form clade in Fig 140 (not in 139 or 141)--> | 3=''Otarocyon'' | 4={{Clade | 1=''Rhizocyon'' | 2={{Clade | label1=Phlaocyonini | 1={{Clade | 1=''Cynarctoides'' | 2=''Phlaocyon'' }} | label2=Borophagini | 2={{Clade | 1=''Cormocyon'' |state1=double | 2={{Clade | 1=''Desmocyon'' |state1=double | 2={{Clade | label1=Cynarctina | 1={{Clade | 1=''Paracynarctus'' | 2=''Cynarctus'' }} | 2={{Clade | 1=''Metatomarctus'' | 2={{Clade | 1=''Euoplocyon'' | 2={{Clade | 1=''Psalidocyon'' | 2={{Clade | 1=''Microtomarctus'' | 2={{Clade | 1=''Protomarctus'' | 2={{Clade | 1=''Tephrocyon'' | label2=Aelurodontina | 2={{Clade | 1=''Tomarctus'' |state1=double | 2=''Aelurodon'' }} | label3=Borophagina | 3={{Clade | 1=''Paratomarctus'' | 2={{Clade | 1=''Carpocyon'' | 2={{Clade | 1=''Protepicyon'' | 2={{Clade | 1=''Epicyon'' | 2=''Borophagus'' }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }}
==Extinction== According to an analysis of the fossil record of North American fossil carnivorans, the decline of borophagines from a diversity of about 30 species 15 million years ago to extinction was largely driven by competition with felids and canines.<ref name="Silvestro2015" /> Felids invaded the continent from Eurasia about 20 million years ago and were better ambush predators, in part due to their retractable claws.<ref>{{cite web |last=Perry |first=D. |title=Smarts, stealth and retractable claws: Science confirms cats are better than dogs |website=OregonLive.com |publisher=The Oregonian |date=2015-08-14 |archive-date=2015-08-18 |url-status=live |access-date=2016-09-03 |url=http://www.oregonlive.com/living/index.ssf/2015/08/smarts_stealth_and_retractable.html |archive-url=https://web.archive.org/web/20150818073726/http://www.oregonlive.com/living/index.ssf/2015/08/smarts_stealth_and_retractable.html }}</ref> Climate change, which led to the replacement of North American forests with grasslands, may also have been a factor;<ref name="Figueirido2015">{{Cite journal |last1=Figueirido |first1=B. |last2=Martín-Serra |first2=A. |last3=Tseng |first3=Z. J. |last4=Janis |first4=C. M. |date=2015-08-18 |title=Habitat changes and changing predatory habits in North American fossil canids |journal=Nature Communications |volume=6 |pages=7976 |doi=10.1038/ncomms8976 |pmid=26285033|bibcode=2015NatCo...6.7976F |doi-access=free |hdl=10630/32918 |hdl-access=free }}</ref> borophagines were less suited to running down prey than canines.<ref name="Silvestro2015">{{Cite journal |last1=Silvestro |first1=D. |last2=Antonelli |first2=A. |last3=Salamin |first3=N. |last4=Quental |first4=T. B. |year=2015 |title=The role of clade competition in the diversification of North American canids |journal=Proceedings of the National Academy of Sciences |volume=112 |issue=28 |pages=8684–8689 |doi=10.1073/pnas.1502803112 |pmc=4507235 |pmid=26124128|bibcode=2015PNAS..112.8684S |doi-access=free }}</ref> Although these specific species developed powerful limbs that are capable of cracking bones in vicious pounce attacks, other carnivorous species that rely on quick ambush for catching prey were likely more successful than the slower Borophaginae.<ref>{{cite journal | url=https://link.springer.com/article/10.1007/s10914-016-9321-5 | doi=10.1007/s10914-016-9321-5 | title=In the Pursuit of the Predatory Behavior of Borophagines (Mammalia, Carnivora, Canidae): Inferences from Forelimb Morphology | year=2016 | last1=Martín-Serra | first1=Alberto | last2=Figueirido | first2=Borja | last3=Palmqvist | first3=Paul | journal=Journal of Mammalian Evolution | volume=23 | issue=3 | pages=237–249 | s2cid=254698991 | url-access=subscription | hdl=10630/32922 | hdl-access=free }}</ref>
==References== {{Reflist}}
==Further reading== *{{cite book|author1=Wang, X.|author2=Tedford, R. H.|author3=Antón, M.|title=Dogs: Their Fossil Relatives and Evolutionary History|url=https://books.google.com/books?id=degwyTaHLt8C|year=2010|publisher=Columbia University Press|place= New York|isbn=978-0-231-13529-0}} *{{cite book|author=Kathleen Munthe|title=The Skeleton of the Borophaginae (Carnivora, Canidae): Morphology and Function|url=https://books.google.com/books?id=V6zJEV2MEDEC|year=1989|publisher=University of California Press|isbn=978-0-520-09724-7}}
{{Canidae extinct nav}} {{Taxonbar|from=Q2729984}}
Category:Borophagines Category:Mammal subfamilies Category:Pliocene extinctions Category:Oligocene first appearances Category:Taxa described in 1945 Category:Prehistoric animal subfamilies