Gomphotherium land bridge

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Gomphotherium land bridge

Disappearance of native Afro-Arabian predators

← Previous revision Revision as of 11:41, 20 April 2026
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=== Disappearance of native Afro-Arabian predators ===
=== Disappearance of native Afro-Arabian predators ===
[[File:Megistotherium osteothlastes.JPG|thumb|Comparison of various Early to Middle Miocene hyaenodonts that were present during the GOWBI, including the [[Hyainailourinae|hyainailourids]] ''[[Hyainailouros|Hyainailouros sulzeri]]'' (top) and ''[[Megistotherium|Megistotherium osteothlastes]]'' (center), and [[Teratodontidae|teratodontid]] ''[[Dissopsalis pyroclasticus]]''. |left|235x235px]]Prior to the arrival of carnivorans, hyaenodonts were the dominant predators of Afro-Arabia. Despite being successful in Eurasia, many experts suggest competition with carnivorans resulted in the decline and eventual extinction of the hyainailouroids, with carnivorans replacing them in 15 million years.{{Cite journal |last1=Frisica |first1=Anthony R. |last2=Macharwas |first2=Mathew |last3=Muteti |first3=Samuel |last4=Ndiritu |first4=Francis |last5=Rasmussen |first5=D. Tab |date=2 November 2020 |title=A Transitional Mammalian Carnivore Community from the Paleogene–Neogene Boundary in Northern Kenya |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.2020.1833895 |journal=Journal of Vertebrate Paleontology |volume=40 |issue=5 |bibcode=2020JVPal..40E3895F |doi=10.1080/02724634.2020.1833895 |url-access=subscription |doi-access= |article-number=e1833895}} The discovery of ''[[Pakakali]]'' implies small [[Hyainailourinae|hyainailourines]], during the [[Paleogene]], had a diverse diet being similar to that of [[Mesocarnivore|mesocarnivores]] such as [[Gray fox|gray foxes]] and [[ringtail]]. This contrasts small hyainailourines in the Neogene as Miocene hyainailourines similar in size or smaller than ''Pakakli'', such as ''[[Isohyaenodon|Isohyaenodon pilgrimi]]'', ''[[Mlanyama]]'', and ''Metapterodon kaiseri'', showed high levels of specialization towards [[Hypercarnivore|hypercarnivory]]. On the other hand, the abundance of small mesocarnivorous carnivorans present in Afro-Arabia, such as ''[[Kichechia zamanae]]'' and ''[[Leptoplesictis|Leptoplesictis namibiensis]]'', suggests carnivorans quickly dominated this niche after dispersing into the continent. This suggests small hyainailourines may have become hypercarnivorous due to the arrival of the carnivorans.{{Cite journal |last1=Borths |first1=Matthew R. |last2=Stevens |first2=Nancy J. |date=11 October 2017 |editor-last=Smith |editor-first=Thierry |title=The first hyaenodont from the late Oligocene Nsungwe Formation of Tanzania: Paleoecological insights into the Paleogene-Neogene carnivore transition |journal=[[PLOS ONE]] |language=en |volume=12 |issue=10 |bibcode=2017PLoSO..1285301B |doi=10.1371/journal.pone.0185301 |issn=1932-6203 |pmc=5636082 |pmid=29020030 |doi-access=free |article-number=e0185301}} Several experts believed that large hyainailourines, such as ''Hyainailouros'' and ''Megistotherium'', may have found themselves competing against [[pack hunting]] carnivorans. They argued that the larger, more complex brains of the cooperative carnivorans would have prevented the large hyainailourines from effectively defending their kills. However, studies have found that brain size has no correlation with sociality in carnivorans,{{Cite journal |last1=Finarelli |first1=J. A. |last2=Flynn |first2=J. J |date=2009 |title=Brain-size evolution and sociality in Carnivora |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=106 |issue=23 |pages=9345–9349 |bibcode=2009PNAS..106.9345F |doi=10.1073/pnas.0901780106 |pmc=2695124 |pmid=19474299 |doi-access=free}}{{Cite journal |last1=Chambers |first1=Helen Rebecca |last2=Heldstab |first2=Sandra Andrea |last3=O'Hara |first3=Sean J. |date=2021 |title=Why big brains? A comparison of models for both primate and carnivore brain size evolution |journal=PLOS ONE |volume=16 |issue=12 |bibcode=2021PLoSO..1661185C |doi=10.1371/journal.pone.0261185 |pmc=8691615 |pmid=34932586 |doi-access=free |article-number=e0261185}} instead relative size of the anterior brain within carnivoran families likely played a role in sociality instead.{{Cite journal |last1=Vinuesa |first1=Víctor |last2=Iurino |first2=Dawid A. |last3=Madurell-Malapeira |first3=Joan |last4=Liu |first4=Jinyi |last5=Fortuny |first5=Josep |last6=Sardella |first6=Raffaele |last7=Alba |first7=David M. |date=August 2016 |title=Inferences of social behavior in bone-cracking hyaenids (Carnivora, Hyaenidae) based on digital paleoneurological techniques: Implications for human–carnivoran interactions in the Pleistocene |url=https://linkinghub.elsevier.com/retrieve/pii/S1040618215009969 |journal=Quaternary International |language=en |volume=413 |pages=7–14 |bibcode=2016QuInt.413....7V |doi=10.1016/j.quaint.2015.10.037 |url-access=subscription}}{{Cite journal |last1=Sakai |first1=Sharleen T. |last2=Arsznov |first2=Bradley M. |last3=Hristova |first3=Ani E. |last4=Yoon |first4=Elise J. |last5=Lundrigan |first5=Barbara L. |date=2016 |title=Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae |journal=Front Neuroanat |volume=10 |page=99 |doi=10.3389/fnana.2016.00099 |pmc=5071314 |pmid=27812324 |doi-access=free}} Due to the absence of [[Canidae|canids]] (who dispersed into Africa by the latest Miocene{{cite journal |last1=Rook |first1=Lorenzo |date=December 2009 |title=The wide ranging genus ''Eucyon'' Tedford & Qiu, 1996 (Mammalia, Carnivora, Canidae, Canini) in the Mio-Pliocene of the Old World |url=https://zenodo.org/record/5381420 |journal=[[Geodiversitas]] |volume=31 |issue=4 |pages=723–741 |doi=10.5252/g2009n4a723 |s2cid=130345058}}), pack hunting is difficult to assess among carnivorans in early Miocene Africa. Furthermore, vegetation in the early Miocene was generally more closed, preventing pack hunting and shorter, high speed chases from being effective.{{Cite journal |last=Turner |first=Alan |last2=Antón |first2=Mauricio |date=2006 |title=Africa - the Evolution of a Continent and its Large Mammal Fauna |url=https://natuurtijdschriften.nl/pub/523523/CRAN2006023001003.pdf |journal=Cranium |volume=23 |issue=1 |pages=17-40}}
[[File:Megistotherium osteothlastes.JPG|thumb|Comparison of various Early to Middle Miocene hyaenodonts that were present during the GOWBI, including the [[Hyainailourinae|hyainailourids]] ''[[Hyainailouros|Hyainailouros sulzeri]]'' (top) and ''[[Megistotherium|Megistotherium osteothlastes]]'' (center), and [[Teratodontidae|teratodontid]] ''[[Dissopsalis pyroclasticus]]''. |left|235x235px]]Prior to the arrival of carnivorans, hyaenodonts were the dominant predators of Afro-Arabia. Despite being successful in both Africa and Eurasia during and after the Interchange, many experts suggest competition with carnivorans resulted in the decline and eventual extinction of the hyainailouroids, with carnivorans replacing them in 15 million years.{{Cite journal |last1=Frisica |first1=Anthony R. |last2=Macharwas |first2=Mathew |last3=Muteti |first3=Samuel |last4=Ndiritu |first4=Francis |last5=Rasmussen |first5=D. Tab |date=2 November 2020 |title=A Transitional Mammalian Carnivore Community from the Paleogene–Neogene Boundary in Northern Kenya |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.2020.1833895 |journal=Journal of Vertebrate Paleontology |volume=40 |issue=5 |bibcode=2020JVPal..40E3895F |doi=10.1080/02724634.2020.1833895 |url-access=subscription |doi-access= |article-number=e1833895}} The discovery of ''[[Pakakali]]'' implies small [[Hyainailourinae|hyainailourines]], during the [[Paleogene]], had a diverse diet being similar to that of [[Mesocarnivore|mesocarnivores]] such as [[Gray fox|gray foxes]] and [[ringtail]]. This contrasts small hyainailourines in the Neogene as Miocene hyainailourines similar in size or smaller than ''Pakakli'', such as ''[[Isohyaenodon|Isohyaenodon pilgrimi]]'', ''[[Mlanyama]]'', and ''Metapterodon kaiseri'', showed high levels of specialization towards [[Hypercarnivore|hypercarnivory]]. On the other hand, the abundance of small mesocarnivorous carnivorans present in Afro-Arabia, such as ''[[Kichechia zamanae]]'' and ''[[Leptoplesictis|Leptoplesictis namibiensis]]'', suggests carnivorans quickly dominated this niche after dispersing into the continent. This suggests small hyainailourines may have become hypercarnivorous due to the arrival of the carnivorans.{{Cite journal |last1=Borths |first1=Matthew R. |last2=Stevens |first2=Nancy J. |date=11 October 2017 |editor-last=Smith |editor-first=Thierry |title=The first hyaenodont from the late Oligocene Nsungwe Formation of Tanzania: Paleoecological insights into the Paleogene-Neogene carnivore transition |journal=[[PLOS ONE]] |language=en |volume=12 |issue=10 |bibcode=2017PLoSO..1285301B |doi=10.1371/journal.pone.0185301 |issn=1932-6203 |pmc=5636082 |pmid=29020030 |doi-access=free |article-number=e0185301}} Several experts believed that large hyainailourines, such as ''Hyainailouros'' and ''Megistotherium'', may have found themselves competing against [[pack hunting]] carnivorans. They argued that the larger, more complex brains of the cooperative carnivorans would have prevented the large hyainailourines from effectively defending their kills. However, studies have found that brain size has no correlation with sociality in carnivorans,{{Cite journal |last1=Finarelli |first1=J. A. |last2=Flynn |first2=J. J |date=2009 |title=Brain-size evolution and sociality in Carnivora |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=106 |issue=23 |pages=9345–9349 |bibcode=2009PNAS..106.9345F |doi=10.1073/pnas.0901780106 |pmc=2695124 |pmid=19474299 |doi-access=free}}{{Cite journal |last1=Chambers |first1=Helen Rebecca |last2=Heldstab |first2=Sandra Andrea |last3=O'Hara |first3=Sean J. |date=2021 |title=Why big brains? A comparison of models for both primate and carnivore brain size evolution |journal=PLOS ONE |volume=16 |issue=12 |bibcode=2021PLoSO..1661185C |doi=10.1371/journal.pone.0261185 |pmc=8691615 |pmid=34932586 |doi-access=free |article-number=e0261185}} instead relative size of the anterior brain within carnivoran families likely played a role in sociality instead.{{Cite journal |last1=Vinuesa |first1=Víctor |last2=Iurino |first2=Dawid A. |last3=Madurell-Malapeira |first3=Joan |last4=Liu |first4=Jinyi |last5=Fortuny |first5=Josep |last6=Sardella |first6=Raffaele |last7=Alba |first7=David M. |date=August 2016 |title=Inferences of social behavior in bone-cracking hyaenids (Carnivora, Hyaenidae) based on digital paleoneurological techniques: Implications for human–carnivoran interactions in the Pleistocene |url=https://linkinghub.elsevier.com/retrieve/pii/S1040618215009969 |journal=Quaternary International |language=en |volume=413 |pages=7–14 |bibcode=2016QuInt.413....7V |doi=10.1016/j.quaint.2015.10.037 |url-access=subscription}}{{Cite journal |last1=Sakai |first1=Sharleen T. |last2=Arsznov |first2=Bradley M. |last3=Hristova |first3=Ani E. |last4=Yoon |first4=Elise J. |last5=Lundrigan |first5=Barbara L. |date=2016 |title=Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae |journal=Front Neuroanat |volume=10 |page=99 |doi=10.3389/fnana.2016.00099 |pmc=5071314 |pmid=27812324 |doi-access=free}} Due to the absence of [[Canidae|canids]] (who dispersed into Africa by the latest Miocene{{cite journal |last1=Rook |first1=Lorenzo |date=December 2009 |title=The wide ranging genus ''Eucyon'' Tedford & Qiu, 1996 (Mammalia, Carnivora, Canidae, Canini) in the Mio-Pliocene of the Old World |url=https://zenodo.org/record/5381420 |journal=[[Geodiversitas]] |volume=31 |issue=4 |pages=723–741 |doi=10.5252/g2009n4a723 |s2cid=130345058}}), pack hunting is difficult to assess among carnivorans in early Miocene Africa. Furthermore, vegetation in the early Miocene was generally more closed, preventing pack hunting and shorter, high speed chases from being effective.{{Cite journal |last=Turner |first=Alan |last2=Antón |first2=Mauricio |date=2006 |title=Africa - the Evolution of a Continent and its Large Mammal Fauna |url=https://natuurtijdschriften.nl/pub/523523/CRAN2006023001003.pdf |journal=Cranium |volume=23 |issue=1 |pages=17-40}}


== Reason for asymmetry ==
== Reason for asymmetry ==
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