The fossil record of deinotheres in the Jura Mountains and the specific diversity of European deinotheriids
The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland)
Recommendation: posted 30 March 2021, validated 23 April 2021
Proboscideans belong to the Afrotheria, a superorder of mammals with an African origin, which was recently recognized based on molecular data (see review in Asher et al., 2009). The fossil record of Proboscidea is well documented and shows that an important part of their evolutionary history took place in Africa, with their representatives inhabiting the continent for at least 60 million years (Gheerbrant, 2009). However, proboscideans also proved to be great travellers, and a flourishing diversity of proboscidean forms colonized most of the continents of the planet, including Europe, from where they have since completely disappeared. Nowadays, Loxodonta africana, L. cyclotis, and Elephas maximus are flagship species of the African and Asian faunas, but they only represent a minor part of the modern mammalian diversity. In contrast, their ancient relatives seemed to be relatively abundant in past ecosystems (Sanders et al., 2010), which raised a number of interesting, but challenging, questions relative to the structure and evolution of ancient megaherbivore communities (Calandra et al., 2008).
Among proboscideans, deinotheres represent a special case. Their morphology clearly departs from that of other groups, notably in displaying distinctive downward curving lower tusks. Compared to their successful sister group the elephantiforms (i.e., all elephant-like proboscideans closely related to modern elephants; sensu Tassy, 1994), deinotheriids are often regarded as the poor sibling of the Proboscidea for showing a relatively low specific diversity and displaying a reduced morphological variability. In fact, many grey areas still exist regarding the evolution of this unique family.
In their article, Gagliardi et al. (2021) revised the material of deinotheres recovered in the Miocene sands of the Swiss Jura Mountains. They described for the first time the material attributed to Prodeinotherium bavaricum and Deinotherium giganteum from the Delémont valley, and reported the presence of a third species, Deinotherium levius, from the locality of Charmoille in Ajoie. Based on comparisons made on specimens recovered from middle to the late Miocene localities, the authors discussed the potential link between the mode and tempo of deinothere dispersions and the evolution environmental and climatic conditions in Western and Eastern Europe during the Miocene. They also considered the evolution of ecological specializations in the group, especially with regard to size increase.
Gagliardi et al. (2021) proposed to follow the two genera/five species concept (i.e., P. cuvieri, P. bavaricum, D. levius, D. giganteum, and D. proavum), which implies the co-existence of several deinothere species in Europe. The latter hypothesis contrasts with the recognition of a single African Deinotherium species (i.e., D. bozasi) in deposits dated from the late Miocene to the early Pleistocene (Sanders et al., 2010). Such a co-existence of European species was and still is debated; it was here questioned by both reviewers. However, as acknowledged by the authors, only an extensive revision of the material of all recognized species, in Europe and worldwide, will enable to shed more light on the deinothere morphological variability and specific diversity. There is no doubt that such a revision would have a profound impact on our view of the evolution of this enigmatic group.
Asher, R. J., Bennett, N., & Lehmann, T. (2009). The new framework for understanding placental mammal evolution. BioEssays, 31(8), 853–864. doi: 10.1002/bies.200900053
Calandra, I., Göhlich, U. B., & Merceron, G. (2008). How could sympatric megaherbivores coexist? Example of niche partitioning within a proboscidean community from the Miocene of Europe. Naturwissenschaften, 95(9), 831–838. doi: 10.1007/s00114-008-0391-y
Gagliardi, F., Maridet, O., & Becker, D. (2021). The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland). BioRxiv, 244061, ver. 4 peer-reviewed by PCI Paleo. doi: 10.1101/2020.08.10.244061
Gheerbrant, E. (2009). Paleocene emergence of elephant relatives and the rapid radiation of African ungulates. Proceedings of the National Academy of Sciences, 106(26), 10717–10721. doi: 10.1073/pnas.0900251106
Sanders, W. J., Gheerbrant, E., Harris, J. M., Saegusa, H., & Delmer, C. (2010). Proboscidea. In L. Werdelin & W. J. Sanders (Eds.), Cenozoic Mammals of Africa (pp. 161–251). Berkeley: University of California Press. doi: 10.1525/california/9780520257214.003.0015
Tassy, P. (1994). Origin and differentiation of the Elephantiformes (Mammalia, Proboscidea). Verhandlungen Naturwissenschaftlichen Vereins in Hamburg, 34, 73–94.
Lionel Hautier (2021) The fossil record of deinotheres in the Jura Mountains and the specific diversity of European deinotheriids. Peer Community in Paleontology, 100008. 10.24072/pci.paleo.100008
The recommender in charge of the evaluation of the article and the reviewers declared that they have no conflict of interest (as defined in the code of conduct of PCI) with the authors or with the content of the article.
Evaluation round #2
DOI or URL of the preprint: 10.1101/2020.08.10.244061
Version of the preprint: 2
Author's Reply, 19 Mar 2021
Decision by Lionel Hautier, posted 17 Feb 2021
I decided to send again your manuscript to one of the reviewers who recommended major revisions before publishing. Also (s)he acknowledged that this new version is much improved, (s)he also pointed out several issues regarding molar measurements that still need to be carefully considered (see below and the attached file). Until this is done, the manuscript is not ready to be recommended by PCI Paleo.
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Reviewed by anonymous reviewer, 12 Feb 2021
Evaluation round #1
DOI or URL of the preprint: 10.1101/2020.08.10.244061
Author's Reply, 04 Feb 2021
Decision by Lionel Hautier, posted 19 Aug 2020
We have now received two reviews of your manuscript entitled "The record of Deinotheriidae from the Miocene of the Swiss Jura Mountains (Jura Canton, Switzerland)". The reviewers pointed out that your paper contains interesting material, but raised some critical points and presented substantial suggestions how to further improve the manuscript. Both reviewers questioned the co-existence of European deinothere species. They raised important issues regarding specimen stratigraphic positions and species biostratigraphic ranges. They also carefully discussed the taxonomical views adopted throughout the manuscript. I concur with the reviewers that the English style should be improved.
The comments of the two referees are below. Annoted pdfs (Reviewer1 and 2) are also attached to this decision letter. When submitting your revision, please include a rebuttal letter which indicates in details the changes you have made. Also, indicate which of the suggested changes, if any, you have elected not to make and your reasons.
Lionel Hautier PCI Paleo recommender