(a) Arrows indicate possible sauropod
tracks beside the estuary. (b) Viewed in profile, the gentle concave-up
deformation in underlying layers is evident. (c) Arrows indicate possible
sauropod tracks. (d) Tracks have been lightly outlined in white chalk. All
scale bars = 10 cm. Credit: South African Journal of
Science (2026). DOI: 10.17159/sajs.2026/22809
Southern Africa is world renowned
for its fossil record of creatures that lived in the very distant past,
including dinosaurs. But, about 182 million years ago, a huge eruption of lava
covered much of the landscape (the inland Karoo Basin) where most of the
dinosaurs roamed. After that, the dinosaur fossil record in the region goes
abruptly quiet for the Jurassic Period (which lasted from 201 million to 145
million years ago).
Two exciting recent discoveries
confirm, however, that there is more to find of dinosaurs that lived in
southern Africa a long time after those lava flows.
First, dinosaur tracks aged around
140 million years were reported in 2025 on a remote stretch of the coast in
South Africa's Western Cape province. These were the first to be found in the
region from that geological time period (the Cretaceous, 145 million to 66
million years ago).
Now, we've found more in research published in the South
African Journal of Science.
Our work as a team of ichnologists
(studying fossil tracks and traces) often takes us to the Knysna area of the
Western Cape coast, where we investigate tracks in coastal aeolianites (cemented sand dunes) in the age range of 50,000
to 400,000 years old.
During one of these visits, early
in 2025, we decided to visit a small patch of rock that formed during the early
Cretaceous Period. It's the only place in the vicinity where rock of this age
is exposed, and much of it is underwater at high tide. We thought we might be
lucky enough to find a theropod (dinosaur) tooth like the one discovered in those rocks by a 13-year-old boy in 2017.
We were pleasantly surprised when,
instead, Linda Helm, a member of our party, told us in a state of excitement
that she had found dinosaur tracks. Further examination of the deposits
revealed more than two dozen probable tracks.
This so-called Brenton Formation
exposure is tiny, no more than 40 meters in length and five meters in width,
with cliffs rising from the shore to a maximum of five meters. To find dozens
of tracks in this small area suggests a considerable dinosaur presence in the
region during the Cretaceous.
In our study we estimate that these
tracks are 132 million years old, making them the youngest known dinosaur
tracks in southern Africa (50 million years younger than the youngest tracks
reported from the Karoo Basin). They form the second record of dinosaur tracks
from the South African Cretaceous, and the second record from the Western Cape
province. Some of them occur on rock surfaces, while others occur in the cliffs
in profile.
Dinosaur fossil treasures
Southern Africa has a wealth of
vertebrate tracks and traces from the Mesozoic Era (the "Age of Dinosaurs," from 252
million to 66 million years ago, a time span that includes the Jurassic) in
the Karoo Basin—a vast inland basin filled with thick piles of
sedimentary deposits.
Dinosaur tracks from the Triassic and Jurassic periods are abundant in Lesotho and surrounding areas in South Africa's Free State and Eastern Cape provinces.
But vast quantities of lava, now
referred to as the Drakensberg Group, overlaid these track-bearing deposits as a result of
large-scale eruptions. A few dinosaurs appear to have briefly survived the
initial effects of the lava flows, and were probably among the last vertebrates
to inhabit the Karoo Basin.
Then, as the supercontinent
of Gondwana fragmented at the end of the Jurassic Period and
in the early Cretaceous Period, limited Cretaceous terrestrial deposits formed in rift basins in what are now the Western Cape
and Eastern Cape provinces of South Africa.
Dinosaur body fossils have been
reported from those deposits, mostly from the Eastern Cape. They include the
first dinosaur to be identified in the southern hemisphere, now identified as
a stegosaur, as well as sauropods, a coelurosaurian and iguanodontid hatchlings and juveniles.
The only examples of dinosaur
skeletal material from the Western Cape are a few isolated sauropod teeth,
disarticulated bones of a probable sauropod, and two cases from the Knysna
area: the theropod tooth mentioned above and a portion of a tibia.
But now we're after their tracks.
Dinosaurs of Knysna
The tracks we found at Knysna are
in the modern intertidal zone, where the high tide covers most of them twice a
day.
It would be difficult to imagine a
more different scene, 132 million years ago, than the spectacular coastline,
magnificent estuary, and lots of development by humans that we encounter today.
Back in the early Cretaceous, many dinosaurs would have been visible in the
area, perhaps inhabiting tidal channels or point bars (river beaches). The
vegetation would also have been very different from that of today.
The Brenton Formation tracks were
made by theropods, possibly ornithopods (both these kinds of dinosaur were bipedal,
walking on two legs), and possibly sauropods (huge dinosaurs with very long necks and very
long tails that were quadrupedal, walking on four legs). Theropods were meat
eaters, while ornithopods and sauropods were plant eaters.
It can be challenging at times to
distinguish theropod tracks from ornithopod tracks. Sauropod tracks are larger
and don't always have clear digit impressions, also sometimes making them hard
to identify with confidence.
In most cases, we have chosen not
to "over-interpret" which types of dinosaurs made which tracks, as
they just aren't clear enough. Our research paper simply intends to document
that dinosaur tracks of this age are relatively plentiful in the Brenton
Formation.
The fact that early Cretaceous
dinosaur tracks have now been identified in both the Robberg
Formation and the
Brenton Formation suggests that more may be found if a search is conducted in
appropriate places. There are a number of other exposures of non-marine
Cretaceous rocks in the Western Cape and Eastern Cape.
Systematic exploration of these deposits is now indicated, in the hope that in addition to finding more dinosaur skeletal material, more dinosaur tracks (and potentially those of other vertebrates) will be identified.
Provided by The Conversation
Source: Fossil hunters uncover 132-million-year-old dinosaur footprints on South Africa's coast
No comments:
Post a Comment