Borophaginae
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The extinct Borophaginae form one of three
subfamilies In biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, ...
found within the
canid Canidae (; from Latin, ''canis'', "dog") is a biological family Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order (biology), order and genus. A family ...
family. The other two canid subfamilies are the extinct
Hesperocyoninae The extinct Hesperocyoninae are one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Borophaginae and extant Caninae. Taxonomic history Hesperocyoninae are basal canids that gave rise to th ...
and extant
Caninae The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most ...
. Borophaginae, called "bone-crushing dogs", were
endemic Endemism is the state of a species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interact ...
to
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

North America
during the
Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define ...
to
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the that extends from 5.333 million to 2.58Hesperocyoninae The extinct Hesperocyoninae are one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Borophaginae and extant Caninae. Taxonomic history Hesperocyoninae are basal canids that gave rise to th ...
. The earliest and most primitive borophagine is the genus ''
Archaeocyon ''Archaeocyon'' ("ancient dog") is an extinct genus of the Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivora ...
'', 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 The Cenozoic ( ; ) is Earth's current geological era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the ge ...

Cenozoic
North America, from small
omnivore An omnivore () is an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular ...
s to powerful,
bear Bears are carnivoran mammals of the family (biology), family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats thr ...

bear
-sized carnivores, such as ''
Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, Canidae, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene to the Hemphill ...

Epicyon
''.


Species

There are 66 identified borophagine species, including 18 new ones that range from the
OrellanThe Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), 34-32 million years ago. It is usually considered to fall within the Early Oligocene. T ...
to
BlancanThe Blancan North American Stage on the geologic timescale The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists ...
ages. A
phylogenetic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, ...

phylogenetic
analysis of the species was conducted using
cladistic Cladistics (; ) is an approach to Taxonomy (biology), biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically ...

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 Phlaocyonini is an extinction, extinct clade or tribe (biology), tribe of hypocarnivore, hypocarnivorous Borophaginae, borophagines (bone-crushing dogs). They were endemic to North America and from the Oligocene epoch (Whitneyan stage) to the Mioc ...
, 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 ''Archaeocyon'' ("ancient dog") is an extinct genus of the Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivora ...
'', ''Oxetocyon'', ''Otarocyon'', and ''Rhizocyon'', in the
OrellanThe Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), 34-32 million years ago. It is usually considered to fall within the Early Oligocene. T ...
through early Arikareean stages. 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. Their good fossil record has also allowed a detailed reconstruction of their phylogeny, showing that the group was highly diverse in its heyday. 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 The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most ...
have only four toes normally. Noteworthy genera in this group are ''Aelurodon'', ''
Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, Canidae, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene to the Hemphill ...

Epicyon
'', and ''Borophagus'' (=''Osteoborus''). According to Xiaoming Wang (paleontologist), 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.


Classification

Borophagine taxonomy, following Wang et al. (million years=in existence) *Family Canidae **Subfamily †Borophaginae ***†''
Archaeocyon ''Archaeocyon'' ("ancient dog") is an extinct genus of the Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivora ...
'' 33—26 Ma, existing ***†''Oxetocyon'' 33—28 Ma, existing ***†''Otarocyon'' 34—30 Ma, existing ***†''Rhizocyon'' 33—26 Ma, existing ***Tribe †
Phlaocyonini Phlaocyonini is an extinction, extinct clade or tribe (biology), tribe of hypocarnivore, hypocarnivorous Borophaginae, borophagines (bone-crushing dogs). They were endemic to North America and from the Oligocene epoch (Whitneyan stage) to the Mioc ...
33—13 Ma, existing ****†''Cynarctoides'' 30—18 Ma, existing ****†''Phlaocyon'' 30—19 Ma, ***Tribe †Borophagini 30—3 Ma, existing ****†''Cormocyon'' 30—20 Ma, existing ****†''Desmocyon'' 25—16 Ma, existing ****†''Metatomarctus'' 19—16 Ma, existing ****†''Euoplocyon'' 18—16 Ma, existing ****†''Psalidocyon'' 16—13 Ma, existing ****†''Microtomarctus'' 21—13 Ma, existing ****†''Protomarctus'' 20—16 Ma, existing ****†''Tephrocyon'' 16—14 Ma, existing ****Subtribe †Cynarctina 20—10 Ma, existing *****†''Paracynarctus'' 19—16 Ma, existing *****†''Cynarctus'' 16—12 Ma, existing ****Subtribe †Aelurodontina 20—5 Ma, existing *****†''Tomarctus'' 23—16 Ma, existing *****†''Aelurodon'' 16—12 Ma, existing ****Subtribe †Borophagina *****†''Paratomarctus'' 16—5 Ma, existing *****†''Carpocyon'' 16—5 Ma, existing *****†''Protepicyon'' 16—12 Ma, existing *****†''
Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, Canidae, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene to the Hemphill ...

Epicyon
'' 12—10 Ma, existing *****†''Borophagus'' (=''Osteoborus'') 12—5 Ma, existing Cladogram showing borophagine interrelationships, following Wang et al., figure 141:


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 Caninae, canines. Felids invaded the continent from Eurasia about 20 million years ago and were better ambush predators, in part due to their retractable claws. Climate change, which led to the replacement of North American forests with grasslands, may also have been a factor; borophagines were less suited to running down prey than canines. 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. Martín-Serra, A., Figueirido, B. & Palmqvist, P. In the Pursuit of the Predatory Behavior of Borophagines (Mammalia, Carnivora, Canidae): Inferences from Forelimb Morphology. J Mammal Evol 23, 237–249 (2016)


References


Further reading

* * {{Taxonbar, from=Q2729984 Borophagines, Mammal subfamilies Pliocene extinctions Oligocene first appearances Fossil taxa described in 1945