Title: Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty
Old World monkeys (Cercopithecoidea) are a highly successful primate radiation, with more than 130 living species and the broadest geographic range of any extant group except humans. Although cercopithecoids are highly variable in habitat use, social behavior, and diet, a signature dental feature unites all of its extant members: bilophodonty (bi: two, loph: crest, dont: tooth), or the presence of two cross-lophs on the molars. This feature offers an adaptable Bauplan that, with small changes to its individual components, permits its members to process vastly different kinds of food. Old World monkeys diverged from apes perhaps 30 million years ago (Ma) according to molecular estimates, and the molar lophs are sometimes incompletely developed in fossil species, suggesting a mosaic origin for this key adaptation. However, critical aspects of the group’s earliest evolution remain unknown because the cercopithecoid fossil record before ∼18 Ma consists of only two isolated teeth, one from Uganda and one from Tanzania. Here we describe a primitive Old World monkey from Nakwai, Kenya, dated at ∼22 Ma, that offers direct evidence for the initial key steps in the evolution of the cercopithecoid dentition. The simple dentition and absence of bilophodonty in the Nakwai monkey indicate that the initial radiation of Old World monkeys was first characterized by a reorganization of basic molar morphology, and a reliance on cusps rather than lophs suggests frugivorous diets and perhaps hard object feeding. Bilophodonty evolved later, likely in response to the inclusion of leaves in the diet.
Arenson, Julia L.; Sargis, Eric J.; Hart, John A.; Hart, Terese B.; Detwiler, Kate M.; Gilbert, Christopher C.(
, American Journal of Physical Anthropology)
AbstractObjectives
The guenons (tribe Cercopithecini) are a diverse and primarily arboreal radiation of Old World monkeys from Africa. However, preliminary behavioral observations of the lesula (Cercopithecus lomamiensis), a little‐known guenon species described in 2012, report it spending substantial amounts of time on the ground. New specimens allow us to present the first description of lesula postcranial morphology and apply a comparative functional morphology approach to supplement our knowledge of its locomotor behavior.
Materials and methods
To infer the substrate use preferences of the lesula, 22 postcranial variables correlated with locomotion were assessed in a sample of 151 adult guenon specimens, including twoC. lomamiensis. Using multivariate statistical analyses, we predict the amount of time the lesula spends on the ground relative to the comparative sample.
Results
Results suggest that the lesula spends nearly half its time on the ground, and the two available individuals were classified as semiterrestrial and terrestrial with strong support. Comparisons with two outgroup cercopithecid taxa (Colobus guerezaandMacaca mulatta) demonstrate that, as a group, guenons retain signals of a generalized, semiterrestrially adapted postcranium compared to specialized arboreal cercopithecids.
Discussion
These results corroborate preliminary behavioral observations of the lesula as a semiterrestrial to terrestrial primate and imply multiple evolutionary transitions in substrate use among the guenon radiation. A broader view of cercopithecoid evolution suggests that a semiterrestrial ancestor for extant guenons is more parsimonious than an arboreal one, indicating that the arboreal members of the group are probably recently derived from a more semiterrestrial ancestor.
Funston, Gregory F.; dePolo, Paige E.; Shelley, Sarah L.; Wible, John R.; Williamson, Thomas E.; Brusatte, Stephen L.(
, Vertebrate anatomy morphology palaeontology)
null
(Ed.)
The rise of mammals after the extinction of the dinosaurs remains one of the most enigmatic intervals in the evolution of mammals. A relatively sparse Paleocene fossil record and confusing interrelationships between taxa means that little is known of the evolution, ecology, and biology of these animals. As a result, the life history of these organisms is completely unstudied, despite likely playing a key role in the ability of these clades to rapidly proliferate and increase in body size in recovering ecosystems. However, intensive collection efforts in the San Juan Basin of New Mexico in the last decade have drastically improved the record of many Paleocene mammals, and offer the first opportunity to address questions about the life history of these animals. Here, we present preliminary results of an in-depth paleohistological analysis of Pantolambda bathmodon, an early, possibly gregarious pantodont, using an ontogenetic series of individuals. Pantodonts were bizarre, herbivorous eutherians
of unknown phylogenetic affinity, and were among the first mammal lineages to reach large body sizes in the Paleocene. In examining both dental and skeletal records of growth from the same individuals, including a juvenile still bearing deciduous teeth, our study is among the most comprehensive paleohistological analyses of any fossil mammal. This intensive approach allows for unprecedented insights into the life history of this species. Neonatal lines in the teeth indicate that the deciduous premolars and the first upper molar were erupted prior to birth, similar to precocious, nidifugous mammals today. Daily incremental lines in the enamel and dentine suggest rapid crown formation times (~45–70 days) and a gestation period of at least 15 weeks. A stress line in the postcranial bones, recording an anomalous decrease in growth towards the end of this individual’s life, may represent the weaning event. In the absence of geochemical evidence, it is unclear which of two stress lines in the teeth corresponds to this event, but these lines occur roughly one and two months after birth, respectively. The weanling perished approximately 2.5 months after birth, weighing about 17 kg. An adult individual exhibiting severe wear on the dentition allows us to estimate maximum longevity in Pantolambda bathmodon at about 7 years. In comparison with life history data on living mammals from the PanTheria dataset, Pantolambda bathmodon had a gestation length and weaning duration below average for a placental of its adult body size (42 kg), but within the range of known variation. However, its lifespan was exceptionally short, falling outside the bounds of comparable living mammals. Together, these lines of evidence suggest a relatively rapid pace of life in Pantolambda bathmodon, despite its relatively large body size. Ongoing sampling of more individuals and geochemical
analyses should allow for estimation of time to sexual maturity and help to confirm the identity of the weaning line, completing our picture of the life history of this pioneering species.
Marciniak, Stephanie; Mughal, Mehreen R.; Godfrey, Laurie R.; Bankoff, Richard J.; Randrianatoandro, Heritiana; Crowley, Brooke E.; Bergey, Christina M.; Muldoon, Kathleen M.; Randrianasy, Jeannot; Raharivololona, Brigitte M.; et al(
, Proceedings of the National Academy of Sciences)
No endemic Madagascar animal with body mass >10 kg survived a relatively recent wave of extinction on the island. From morphological and isotopic analyses of skeletal “subfossil” remains we can reconstruct some of the biology and behavioral ecology of giant lemurs (primates; up to ∼160 kg) and other extraordinary Malagasy megafauna that survived into the past millennium. Yet, much about the evolutionary biology of these now-extinct species remains unknown, along with persistent phylogenetic uncertainty in some cases. Thankfully, despite the challenges of DNA preservation in tropical and subtropical environments, technical advances have enabled the recovery of ancient DNA from some Malagasy subfossil specimens. Here, we present a nuclear genome sequence (∼2× coverage) for one of the largest extinct lemurs, the koala lemur Megaladapis edwardsi (∼85 kg). To support the testing of key phylogenetic and evolutionary hypotheses, we also generated high-coverage nuclear genomes for two extant lemurs, Eulemur rufifrons and Lepilemur mustelinus , and we aligned these sequences with previously published genomes for three other extant lemurs and 47 nonlemur vertebrates. Our phylogenetic results confirm that Megaladapis is most closely related to the extant Lemuridae (typified in our analysis by E. rufifrons ) to the exclusion of L. mustelinus , which contradicts morphology-based phylogenies. Our evolutionary analyses identified significant convergent evolution between M. edwardsi and an extant folivore (a colobine monkey) and an herbivore (horse) in genes encoding proteins that function in plant toxin biodegradation and nutrient absorption. These results suggest that koala lemurs were highly adapted to a leaf-based diet, which may also explain their convergent craniodental morphology with the small-bodied folivore Lepilemur .
Kynigopoulou, Z.; Shelley, S. L.; Williamson, T. E.; Brusatte, S. L.(
, Journal of Vertebrate Paleontology, Abstracts and Programs)
After the Cretaceous-Paleogene (K-Pg) mass extinction mammals, which originated during the Mesozoic, managed to survive and thrive. However, the tempo and mode of evolution for eutherians (placentals and close relatives) after the extinction are still unclear. An ideal group to investigate the post KPg evolution of mammals is the taeniodonts, as they are among the few taxa to purportedly cross the boundary. They then underwent a radiation in the early Paleogene and are defined primarily by their unusual dentition which is suited to chew an abrasive and tough diet. Ten genera of taeniodonts are currently recognized and are commonly arranged into two families. The Conoryctidae is usually considered to have a more generalized body plan while Stylinodontidae possess relatively extreme digging adaptations and more highly derived dentitions with enlarged canines. We conducted a
phylogenetic analysis by applying parsimony and Bayesian techniques to a dataset of characters gathered from extensive observation of new specimens.
We found limited support for the conoryctid-stylinodontid division and the genera Conoryctes and Onychodectes are placed as key basal taxa outside the clade of the more robust derived taxa (Wortmania, Ectoganus, Psittacotherium, Stylinodon). We then assessed postcranial bones to determine functional modes for taeniodonts and to test changes across
phylogeny. Qualitatively, most taeniodonts, including Onychodectes, possess indicators of digging, i.e., a well-developed deltopectoral crest and broad distal end of the humerus for increasing flexion, pronation and supination, a long olecranon process of the ulna and enlarged manual unguals. Then we conducted quantitative multivariate analyses (linear discriminant analysis), using 9 forelimb linear measurements and 29 tarsal ones, comparing
taeniodonts to a suite of extant mammals with known locomotor mode and other Paleogene taxa. Our results suggest Onychodectes to be terrestrial/semifossorial and comparable with the numbat (Myrmecobius fasciatus).
Ectoganus and Stylinodon are semi-fossorial and fall out near the gopher,
Pappogeomys merriami and the aardvark (Orcyteropus afer). Therefore, our
study indicates that digging behaviors are ancestral for taeniodonts, and
suggest that burrowing may have been integral to their survival across the KPg
boundary and their subsequent radiation.
Grant Information:
European Research Council Starting Grant (ERC StG 2017, 756226, PalM), National Science Foundation (EAR- 1325544, 1654952, DEB-1654952, 1654949)
Taylor, Catherine E.; Brasil, Marianne F.; Monson, Tesla A.; Yohler, Ryan M.; Hlusko, Leslea J.(
, American Journal of Biological Anthropology)
AbstractObjectives
The goals of this study were to describe and interpret two new fossil assemblages of cercopithecin monkeys (n = 328), one from the Faro Daba beds (ca. 100,000 years) and the other one from the Chai Baro beds (>158,000 years old), in the Afar Rift of Ethiopia.
Materials and Methods
We describe the two assemblages and compare them to extant cercopithecin species and the smaller fossil assemblage from Asbole, Ethiopia (ca. 600 ka). We use a population‐based approach to the taxonomy given the unusually large number of specimens. Craniodental and postcranial anatomy are presented. Evidence of locomotor habitus is described and evaluated in a framework of hybridization and postcranial plasticity.
Results
We attribute all cercopithecin specimens from both beds to cf.Chlorocebusand conclude that the Faro Daba and Chai Baro assemblages likely sample single species at each time horizon. Subtle differences between the two assemblages, mostly in postcranial morphology, are insufficient to justify separation at the species level.
Discussion
The large sample sizes and unique preservational aspects of these two assemblages open a new window into the recent evolution of guenons. Our data indicate that these fossil populations may be ancestral to the cercopithecins currently living in the Afar region of Ethiopia.
Rasmussen, D. Tab, Friscia, Anthony R., Gutierrez, Mercedes, Kappelman, John, Miller, Ellen R., Muteti, Samuel, Reynoso, Dawn, Rossie, James B., Spell, Terry L., Tabor, Neil J., Gierlowski-Kordesch, Elizabeth, Jacobs, Bonnie F., Kyongo, Benson, Macharwas, Mathew, and Muchemi, Francis. Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty. Proceedings of the National Academy of Sciences 116.13 Web. doi:10.1073/pnas.1815423116.
Rasmussen, D. Tab, Friscia, Anthony R., Gutierrez, Mercedes, Kappelman, John, Miller, Ellen R., Muteti, Samuel, Reynoso, Dawn, Rossie, James B., Spell, Terry L., Tabor, Neil J., Gierlowski-Kordesch, Elizabeth, Jacobs, Bonnie F., Kyongo, Benson, Macharwas, Mathew, & Muchemi, Francis. Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty. Proceedings of the National Academy of Sciences, 116 (13). https://doi.org/10.1073/pnas.1815423116
Rasmussen, D. Tab, Friscia, Anthony R., Gutierrez, Mercedes, Kappelman, John, Miller, Ellen R., Muteti, Samuel, Reynoso, Dawn, Rossie, James B., Spell, Terry L., Tabor, Neil J., Gierlowski-Kordesch, Elizabeth, Jacobs, Bonnie F., Kyongo, Benson, Macharwas, Mathew, and Muchemi, Francis.
"Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty". Proceedings of the National Academy of Sciences 116 (13). Japan: Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.1815423116.https://par.nsf.gov/biblio/10087865.
@article{osti_10087865,
place = {Japan},
title = {Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty},
url = {https://par.nsf.gov/biblio/10087865},
DOI = {10.1073/pnas.1815423116},
abstractNote = {Old World monkeys (Cercopithecoidea) are a highly successful primate radiation, with more than 130 living species and the broadest geographic range of any extant group except humans. Although cercopithecoids are highly variable in habitat use, social behavior, and diet, a signature dental feature unites all of its extant members: bilophodonty (bi: two, loph: crest, dont: tooth), or the presence of two cross-lophs on the molars. This feature offers an adaptable Bauplan that, with small changes to its individual components, permits its members to process vastly different kinds of food. Old World monkeys diverged from apes perhaps 30 million years ago (Ma) according to molecular estimates, and the molar lophs are sometimes incompletely developed in fossil species, suggesting a mosaic origin for this key adaptation. However, critical aspects of the group’s earliest evolution remain unknown because the cercopithecoid fossil record before ∼18 Ma consists of only two isolated teeth, one from Uganda and one from Tanzania. Here we describe a primitive Old World monkey from Nakwai, Kenya, dated at ∼22 Ma, that offers direct evidence for the initial key steps in the evolution of the cercopithecoid dentition. The simple dentition and absence of bilophodonty in the Nakwai monkey indicate that the initial radiation of Old World monkeys was first characterized by a reorganization of basic molar morphology, and a reliance on cusps rather than lophs suggests frugivorous diets and perhaps hard object feeding. Bilophodonty evolved later, likely in response to the inclusion of leaves in the diet.},
journal = {Proceedings of the National Academy of Sciences},
volume = {116},
number = {13},
publisher = {Proceedings of the National Academy of Sciences},
author = {Rasmussen, D. Tab and Friscia, Anthony R. and Gutierrez, Mercedes and Kappelman, John and Miller, Ellen R. and Muteti, Samuel and Reynoso, Dawn and Rossie, James B. and Spell, Terry L. and Tabor, Neil J. and Gierlowski-Kordesch, Elizabeth and Jacobs, Bonnie F. and Kyongo, Benson and Macharwas, Mathew and Muchemi, Francis},
}
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