An international team of geophysicists has uncovered compelling evidence that tectonic activity approximately 20 million years ago created a land bridge between Eurasia and Africa via the Arabian Peninsula. This geological event facilitated the migration of various animal species, including the ancestors of modern elephants, giraffes, and hominins, from Eurasia into Africa, which had been relatively isolated since the breakup of the supercontinent Gondwana.
The formation of this land bridge resulted from the collision between the Arabian and Eurasian tectonic plates. This collision led to the uplift of the Arabian Peninsula and the closure of the Tethys Seaway, effectively splitting it into what are now the Mediterranean and Arabian Seas. The closure of the Tethys Seaway had significant climatic and ecological consequences, including alterations in ocean circulation patterns and the aridification of regions such as the Sahara Desert.
The newly formed land connection enabled a significant faunal exchange between Eurasia and Africa, known as the Proboscidean Datum Event. This event is marked by the migration of proboscideans (elephant ancestors) and other species into Africa, as well as the dispersal of African species into Eurasia . This biogeographical interchange had profound implications for the evolutionary trajectories of numerous species, including primates.
What was the timeline and evolutionary sequence of the African proboscideans? The African proboscideans—members of the order Proboscidea, which includes modern elephants—have a rich evolutionary history extending back over 60 million years. The evolutionary timeline in Africa covers numerous lineages, often overlapping temporally and geographically. Here's a detailed overview of their evolutionary sequence and timeline:Subsequent to this initial migration, the land bridge continued to serve as a conduit for species movement. Notably, it facilitated the later migration of hominins, including Homo sapiens, out of Africa into Eurasia. This migratory pattern is well-documented in the fossil record and aligns with genetic evidence supporting the "Out of Africa" theory of human evolution.
Palaeocene–Eocene (~60–34 million years ago)
- Earliest Proboscideans
- Proboscideans likely originated in Africa from small, semi-aquatic ancestors resembling today's hyraxes (order Hyracoidea) and sirenians (sea cows). These earliest forms are not yet clearly identified but are inferred from related taxa.
- The earliest definite proboscidean fossils date from the late Palaeocene–early Eocene (~55–50 million years ago).
Eocene–Oligocene (34–23 million years ago)
- Moeritherium (Late Eocene–Early Oligocene)
- Semi-aquatic, small-bodied animals, resembling tapirs or pygmy hippos, with small tusks and an elongated but modest trunk structure.
- Dates: ~37–30 million years ago (mya).
- Numidotherium (Late Eocene)
- Larger than Moeritherium, terrestrial browsing lifestyle, early trunk and enlarged upper incisors.
- Dates: ~37–33 mya.
- Barytherium (Late Eocene–Early Oligocene)
- Early large-bodied proboscidean, heavier build, longer skull, and prominent tusks.
- Dates: ~35–30 mya.
Late Oligocene–Early Miocene (28–16 million years ago)
- Palaeomastodon
- More advanced trunk structure, robust limbs, adapted for terrestrial browsing lifestyle, significant size increase.
- Dates: ~35–28 mya.
- Phiomia
- Further tusk enlargement and trunk evolution; adapted to terrestrial browsing and grazing.
- Dates: ~30–25 mya.
Middle–Late Miocene (16–5 million years ago)
- Gomphotheres
- Several gomphothere taxa (e.g., Gomphotherium, Choerolophodon) appear in Africa, some spreading into Eurasia. Gomphotheres had characteristic shovel-like lower tusks.
- Dates: ~16–5 mya.
- Deinotherium
- Giant proboscideans with distinctive downward-curving lower tusks; leaf browsers inhabiting diverse wooded habitats.
- Dates: ~20–2 mya.
Late Miocene–Pliocene (7–2 million years ago)
- Primelephas
- Direct ancestor of modern elephants; emergence of more specialised molars and elongated trunks.
- Dates: ~7–4 mya.
- Divergence into three major lineages from Primelephas:
- Loxodonta lineage → Modern African elephants.
- Elephas lineage → Modern Asian elephants (migrated to Asia).
- Mammuthus lineage → Mammoths (primarily migrated out of Africa into Eurasia and North America).
Pleistocene to Present (2.5 million years ago–Present)
- Genus Loxodonta (African Elephants)
- Other notable lineages that co-existed and then went extinct:
- Loxodonta adaurora (Pliocene–Early Pleistocene), transitional species leading to:
- Loxodonta atlantica (Late Pliocene–Early Pleistocene), extinct.
- Modern species:
- Loxodonta africana (African savanna elephant)
- Loxodonta cyclotis (African forest elephant)
- Deinotherium persisted until about 1 million years ago.
- Stegodon (primarily Asian, but some African representatives).
Summary of Major Proboscidean Evolutionary Trends in Africa:
- From semi-aquatic, small-bodied forms (Moeritherium) to larger terrestrial browsers (Palaeomastodon, Phiomia).
- Increasing body size, more specialised teeth for browsing and grazing, and development of trunks.
- Extensive diversification through Miocene and Pliocene, with a proliferation of forms adapted to a variety of ecological niches.
- Eventual domination and survival of the Loxodonta lineage, which led to today’s African elephants.
This overview provides a general chronological framework, demonstrating the diversity and adaptive radiation of proboscideans in Africa over tens of millions of years, culminating in today's elephants.
The research detailing these findings has been published in the journal Nature Reviews Earth & Environment and further elaborated in a news release by the Jackson School of Geosciences at the University of Texas.
How Activity in Earth’s Mantle Led the Ancient Ancestors of Elephants, Giraffes, and Humans into Asia and Africa
What roils beneath the Earth’s surface may feel a world away, but the activity can help forge land masses that dictate ocean circulation, climate patterns, and even animal activity and evolution. In fact, scientists believe that a plume of hot rocks that burst from the Earth’s mantle millions of years ago could be an important part in the story of human evolution.
In a paper published in Nature Reviews Earth & Environment, an international team of researchers investigated the formation of a large land bridge that connected Asia and Africa 20 million years ago, through what is now the Arabian Peninsula and Anatolia.
The paper brings together previously published research with new models created at The University of Texas at Austin Jackson School of Geosciences and the GFZ Helmholtz Centre for Geosciences.
This gradual uplift of land enabled the early ancestors of animals such as giraffes, elephants, rhinoceroses, cheetahs, and even humans, to roam between Africa and Asia. The appearance of the land ended a 75-million-year-long isolation of Africa from other continents.
This study has relevance to the question of ‘How did our planet change, in general? What are the connections between life and tectonics?
Professor Thorsten W. Becker, co-author
University of Texas Institute for Geophysics (UTIG) & Department of Earth and Planetary Sciences (EPS),
Jackson School of Geosciences
University of Texas at Austin, Austin, TX, USA.
The story begins 50-60 million years ago, when a slab of rock sliding into the Earth’s mantle created a “conveyor belt” for hot rocks to boil up in an underground plume that reached the surface some 30 million years later. This convective activity in the mantle, coupled with the collision of tectonic plates, created an uplift in land that contributed to closing the ancient Tethys Sea, splitting it into what is now the Mediterranean and Arabian Seas, and created a landmass that bridged Asia and Africa for the first time.
The study’s lead author Eivind Straume analyzed the wide-ranging consequences of this geologic activity while he was a postdoctoral fellow at the Jackson School. He said the appearance of the land bridge and animal evolution go hand in hand.
The shallow seaway closed several million years before it otherwise likely would have due to these specific processes — mantle convection and corresponding changes in dynamic topography. Without the plume, you could argue that the continental collision would have been different.
Dr. Eivind O. Straume, first author
NORCE Norwegian Research Centre & The Bjerknes Centre for Climate Research
Bergen, Norway.
In this case, timing is everything. If it had been an additional million years before Africa and Asia were connected, the animals that made their way into and out of Africa could have been on a different evolutionary path. That includes the ancestors of today’s humans.
Several million years before the land bridge had completely closed, the primate ancestors of humans came to Africa from Asia. While those primates ended up going extinct in Asia, their lineages diversified in Africa. Then when the land bridge fully emerged, these primates re-colonized Asia.
It’s an example of how the long-term convective evolution of the planet talks to the evolution of life.
Dr. Eivind O. Straume.
This uplift of the Arabian Peninsula also had significant impacts on ocean circulation and the Earth’s climate. Nearby ocean temperatures warmed, which in turn widened seasonal temperature ranges, and made a swath of land from north Africa to central Asia more arid. Researchers believe the formation of this land bridge was a final trigger in making the Sahara a desert. And these topographical changes enhanced monsoon season in Asia, making southeast Asia wetter.
This paper brings together existing research spanning plate tectonics, mantle convection, topography and paleogeography, evolutionary anthropology, mammal evolution, climate evolution, and ocean circulation, among other topics, to tell a cohesive story of the wide-ranging effects of these mantle dynamics.
To us at least, this is a compelling — perhaps a little bit provocative — summary of recent advancements.
Professor Thorsten W. Becker.
Publication:
The paleogeography of much of Africa, Europe, and Asia over the last 65 million years is shown on the left, and the backward advected mantle density anomalies is on the right. It also shows the corresponding changes in dynamic topography.Credit: Eivind Straume
AbstractFor those of them who understand it, this finding is a problem for creationists on a number of counts.
The Tethys Seaway once linked the Atlantic and Indo-Pacific oceans. Its gradual shallowing and closure impacted global ocean circulation, faunal diversification and climatic changes. In this Review, we evaluate the tectonic causes and the topographic changes across the Eastern Mediterranean over the past 66 Ma and explore the consequences of Tethys Seaway closure. Mantle convection led to collisional tectonic processes, mountain building and crustal thickening along the Tethyan realm. The Ethiopian flood basalts mark the arrival of the Afar plume at ~30 Ma, followed by northward-trending volcanic activity indicating that plume material had moved to northwest Arabia by ~20 Ma. Plume-induced mantle flow generated kilometre-scale uplift across East Africa, at ~8° N at ~35 Ma, and along Arabia and led to the formation of the Gomphotherium land bridge at 30° N, ~20 Ma. Afro-Arabian uplift contributed to the development of modern-like Asian monsoons, and the land bridge between Africa and Asia enabled one of the greatest faunal interchanges of the Cenozoic. The gradual shoaling and final closure of the Tethys Seaway likely facilitated the transition towards a stronger overturning circulation in the North Atlantic, contributing to the Cenozoic cooling trend. Future research should incorporate more detailed spatial and temporal uplift models into paleogeography and paleoclimate models to better simulate consequences for ocean circulation, climate and biogeographic dispersals.
Straume, E.O., Faccenna, C., Becker, T.W. et al.
Collision, mantle convection and Tethyan closure in the Eastern Mediterranean.
Nat Rev Earth Environ 6, 299–317 (2025). https://doi.org/10.1038/s43017-025-00653-2
© 2025 Springer Nature Ltd.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
Perhaps most obviously, is that these geological changes occur over millions of years - far longer than the 6-10,000 years creationists believe Earth has existed for, and consistent with the Theory of Evolution which requires such long time scales.
Creationists often argue for fixed, distinct "kinds" that were created separately and did not diversify or migrate extensively. However, this geological and fossil evidence directly demonstrates how species migration, facilitated by shifting landmasses, shaped evolutionary history. Such findings highlight the interconnectedness of species across continents, undermining the claim of independent creation events and reinforcing the evolutionary narrative of descent with modification.
Moreover, creationists frequently claim that evolution lacks transitional fossils and fails to align with geological history. This discovery clearly maps significant geological events—like the closure of the Tethys Sea and the creation of the Arabia land bridge—onto biological events documented in the fossil record. The correspondence between tectonic shifts and evolutionary milestones such as the diversification of elephants, giraffes, and primates decisively refutes the creationist assertion of unrelated species spontaneously appearing. Instead, it illustrates a clear causal relationship between environmental changes and evolutionary adaptation, precisely the pattern predicted by evolutionary theory.
Lastly, creationism struggles to explain why organisms display geographic distributions and fossil patterns consistent with past land connections and migrations. If each species was independently created, their global distribution would presumably reflect isolated creation rather than migratory histories shaped by geological processes. This study directly contradicts such claims by demonstrating that migration patterns of species—including human ancestors—are closely tied to Earth's dynamic geological history. It thus provides yet another powerful, evidence-based rebuttal to the static, supernatural model offered by creationism.
Just another scientific finding for creationists to lie about, misrepresent or ignore, but never acknowledge as the problem it is for them.
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