Pliocene crocodiles from Kanapoi, Turkana Basin, Kenya

Brochu, Christopher A.

doi:10.1016/j.jhevol.2017.10.003

Cited by 16 publications

(22 citation statements)

References 65 publications

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“…He concluded that even if it could be a homoplastic character, the promontorium should be considered a synapomorphy of the group on the basis of the knowledge of that time. The first, and up to now only, phylogenetic analysis that evaluated the relationships of C. checchiai 9,26 confirmed the inclusion of this species in the genus Crocodylus, but, having retrieved a broad politomy, lacks of enough resolution to provide precise indications.…”

Section: Discussionmentioning

confidence: 98%

Old African fossils provide new evidence for the origin of the American crocodiles

Delfino

Iurino

Mercurio

et al. 2020

Sci Rep

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Molecular and morphological phylogenies concur in indicating that the African lineages formerly referred to Crocodylus niloticus are the sister taxon the four Neotropical crocodiles (Crocodylus intermedius, C. moreleti, C. acutus and C. rhombifer), implying a transoceanic dispersal from Africa to America. So far the fossil record did not contribute to identify a possible African forerunner of the Neotropical species but, curiously, the oldest remains referred to the African C. niloticus are Quaternary in age, whereas the oldest American fossils of Crocodylus are older, being dated to the early Pliocene, suggesting that another species could be involved. We re-described, also thanks to CT imaging, the only well-preserved topotipic skull of Crocodylus checchiai Maccagno, 1947 from the late Miocene (Messinian) African site of As Sahabi in Libya. As previously suggested on the basis of late Miocene material from Tanzania, C. checchiai is a valid, diagnosable species. According to our phylogenetic analyses, C. checchiai is related to the Neotropical taxa and could be even located at the base of their radiation, therefore representing the missing link between the African and the American lineages. Extant crocodylians are represented by 25 species grouped into 9 genera 1. The most speciose and widespread genus is Crocodylus Laurenti, 1768 that hosts 12 species inhabiting a longitudinally very broad intertropical belt ranging from Australia to South Asia, to Africa and then America. The origin of Crocodylus was placed in the late Miocene (about 13.6-8.3 Ma) of Asia by Oaks 2 , on the basis of a time-calibrated species tree stemming from a DNA analysis, and recently reconstructed as Asian by Nicolai and Mazke 3 on the basis of historical biogeography models. Both the molecular 2,4,5 and the morphological/palaeontological 6-9 approaches, as well as the shared presence of parasites 10 concur in indicating that the origin of the American clade of Crocodylus should be sought in Africa. The four American species Crocodylus intermedius, C. moreleti, C. acutus and C. rhombiferare grouped together with the African Crocodylus niloticus Laurenti, 1768, which is placed at the base of the American branch. According to Meredith et al. 5 , the most parsimonious explanation that takes into consideration both the phylogenetic results and the fossil record of Crocodylus supports a relatively recent transAtlantic crossing of "C. niloticus" from Africa to America. The reason of the inverted commas placed by these authors around the name of Nile crocodile is related to the fact that the eastern and western clades of this species do not cluster together, but are arranged in paraphyly at the base of the American clade, a result shared by different authors applying different molecular techniques 2,4,5,11,12. Hekkala et al. 5 eventually proposed the resurrection of the name Crocodylus suchus Geoffroy Saint-Hilaire, 1807 for the western populations, keeping the name C. niloticus for the (predominantly) eastern populations that is directly at the ...

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Section: Discussionmentioning

confidence: 98%

Old African fossils provide new evidence for the origin of the American crocodiles

Delfino

Iurino

Mercurio

et al. 2020

Sci Rep

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“…The evolution of range‐expansion phenotypes in Crocodylus occurred in a period that is characterized by extinctions in other crocodilians. This large extinction event appears to have been the result of global cooling and aridification that correlated with drops in caimanine diversity, gavialoid extinction in South America, extinction of Australian Mekosuchinae and the loss of European crocodiles (Brochu, ; Brochu et al, ; Delfino et al, ; Moreno‐Bernal, Head, & Jaramillo, ; Salas‐Gismondi et al, ; Scheyer et al, ; Willis, ). In Crocodylus , however, range‐expansion phenotypes appear to be associated with an increase in diversification rates, which is consistent with spatial sorting (Supporting Information Figures S8 and S9).…”

Section: Discussionmentioning

confidence: 99%

“…As such, the higher potential dispersal capabilities observed in Crocodylus might have protected them from the Miocene–Pliocene extinction that influenced overall biodiversity of Crocodyliformes (Bronzati et al, ; Mannion et al, ; Scheyer et al, ) . However, being able to avoid those unfavourable conditions and/or reaching suitable habitat, enabled through higher range‐expansion potential, would have aided in survival (Brochu, ; Delfino et al, ; Moreno‐Bernal et al, ; Salas‐Gismondi et al, ; Willis, ).…”

Section: Discussionmentioning

confidence: 99%

“…Another potential mechanism that might increase speciation rates during or after range‐expansion events is an adaptive radiation, wherein Crocodylus filled the ecological void left after the crocodylomorph extinctions (Marwick, ; Oaks, ). Indeed, Crocodylus now occupies niches that were previously occupied by other crocodile radiations, a pattern seen in Africa (Osteolaeminae), Australia (Mekosuchinae) and the New World (Alligatorids) (Brochu et al, ; Brochu, and references therein). However, a wide range of niches (terrestrial, possibly arboreal species, marine and filter‐feeding species) previously occupied by crocodylomorphs (i.e., by Sebecidae and Mekosuchinae but even Gavialoidea and Caimaniae), were never re‐occupied by Crocodylus , whereas an occupation of as many niches possible is expected in an adaptive radiation (Jouve et al, ; Mannion et al, ; Moreno‐Bernal et al, ; Salas‐Gismondi et al, ; Scheyer et al, ; Wilberg, Turner, & Brochu, ; Willis, ).…”

Section: Discussionmentioning

confidence: 99%

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Trait‐based range expansion aided in the global radiation of Crocodylidae

Nicolaï

Matzke

2019

Global Ecol Biogeogr

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Aim Almost half of the extant species of Crocodylia (nine genera, sensu Benton & Clark) belong to the genus Crocodylus, which originated in the Miocene. Today, this genus has a circumtropical distribution, with representatives found in Asia, Oceania, Africa and the Neotropics. However, its geographical origin and the historical events behind its rapid diversification and global radiation are still debated. Here, we inferred the evolution of a set of life traits that aid in dispersal and how they influenced the biogeography of Crocodylus. Location Global. Time period Cretaceous to the present. Major taxa studied Crocodylidae. Methods We estimated biogeographical history on a published phylogeny using probabilistic biogeography models. Next, we identified four life traits likely to promote range expansion and used a trait‐based dispersal model jointly to infer evolution of these traits and their influence on the dispersal of crocodilians. Finally, we used diversification analyses to identify shifts in diversification rates. Results An Asian origin was reconstructed for Crocodylus. Despite the small size of the phylogeny, statistical model comparison reports substantially improved the model fit of trait‐dependent over trait‐independent dispersal models. In individual tests, the four life traits considered (salt tolerance, large size, large clutches and habitat generalism) appear to be correlated statistically with higher dispersal probabilities. However, the traits are likely to be correlated with each other, and we hypothesize that they all reflect the gradual evolution of a range‐expansion phenotype in early Crocodylus that resulted in increased diversification of the clade. Main conclusions Increased dispersal in the genus Crocodylus was associated with the gradual evolution of a range‐expansion phenotype. Interestingly, the evolution of the range‐expansion phenotype was also associated with the diversification of the genus in a period of global crocodilian extinction, indicating that range expansion might have served as a potential driver of speciation. This suggests that the concept of “spatial sorting”, normally applied at the population genetic level at the leading edge of an expanding population, might also act on a macroevolutionary scale.

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“…By ca. 7 Ma, in the Lower Nawata Formation at Lothagam, near Lake Turkana (Storrs, 2003), the only remaining osteolaemine lineages are Euthecodon and, assuming it is an osteolaemine, Mecistops, both of which persist in the eastern (Gregory) branch of the EARS into the Pleistocene (Joleaud, 1930;Arambourg, 1947;Tchernov, 1986;Storrs, 2003;Brochu, 2020). Although not to the same degree as Euthecodon, Mecistops also has a comparatively slender snout (e.g., Busbey, 1994;Pierce et al, 2008;Sadleir and Makovicky, 2008;Piras et al, 2010;Wilberg, 2017;Groh et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

A new crocodylid from the middle Miocene of Kenya and the timing of crocodylian faunal change in the late Cenozoic of Africa

Cossette¹,

Adams

Drumheller

et al. 2020

J. Paleontol.

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Brochuchus is a small crocodylid originally based on specimens from the early Miocene of Rusinga Island, Lake Victoria, Kenya. Here, we report occurrences of Brochuchus from several early and middle Miocene sites. Some are from the Lake Victoria region, and others are in the Lake Turkana Basin. Specimens from the middle Miocene Maboko locality form the basis of a new species, Brochuchus parvidens, which has comparatively smaller maxillary alveoli. Because of the smaller alveoli, the teeth appear to be more widely spaced in the new species. We also provide a revised diagnosis for Brochuchus and its type species, B. pigotti. A phylogenetic analysis supports a close relationship between Brochuchus and tube-snouted Euthecodon, but although relationships among crocodylids appear poorly resolved in the set of optimal trees, this is because Brochuchus and Euthecodon, along with early Miocene “Crocodylus” gariepensis from the early Miocene of Namibia, jointly adopt two distinct positions—either closely related to the living sharp-nosed crocodile (Mecistops) or to a group including the living dwarf crocodiles (Osteolaemus). Character support for a close relationship with Mecistops is problematic, and we suspect a closer relationship to Osteolaemus will be recovered with improved sampling, but the results here are ambiguous. In either case, Brochuchus is more closely related to living groups not currently found in East Africa. This material helps constrain the timing of crocodylian faunal turnover in the East African Rift Valley System, with endemic lineages largely being replaced by Crocodylus in the middle or late Miocene possibly in response to regional xerification and the replacement of continuous rainforest cover with open grasslands and savannas. UUID: http://zoobank.org/e6f0b219-5f3e-44e5-bdb9-60a4fae8d126

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Pliocene crocodiles from Kanapoi, Turkana Basin, Kenya

Cited by 16 publications

References 65 publications

Old African fossils provide new evidence for the origin of the American crocodiles

Old African fossils provide new evidence for the origin of the American crocodiles

Trait‐based range expansion aided in the global radiation of Crocodylidae

A new crocodylid from the middle Miocene of Kenya and the timing of crocodylian faunal change in the late Cenozoic of Africa

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