Angolasaurus(90 million year oldmarine lizard,also found in Texas)

ANGOLA: MUSEUM IN THE GROUNDGood Fossils

Ocean Currents and Source Rocks

Dinosaur Extinction (K-Pg Boundary)

Louis L. JacobsRoy M. Huffington Department of Earth SciencesSouthern Methodist University, Dallas, Texas

In cooperation with Universidade Agostinho Neto and ISPRA (Lubango). Wehave shown that:

1. The fossils of Angola are a “Museum in the Ground.”

2. The geologic context of the fossils gives clues to past ocean currents and productivity leading to petroleum source rocks.

3. The rocks of Angola record events of worldwide interest, such as the extinction of mosasaurs and dinosaurs, and the precise position of ancient shores.

In 2005 we went to Angola because fossils of giant marine lizards (mosasaurs) had been reported in the 1960’s. Could we find more?

Colleagues at Universidade Agostinho Neto were contacted and we briefly visited the field.

Based on our preliminary trip, the National Geographic Society and the Petroleum Research Fund of the American Chemical Society funded expeditions in 2006 and 2007.

In 2005 we went to Angola because fossils of giant marine lizards (mosasaurs) had been reported in the 1960’s. Could we find more?

Colleagues at Universidade Agostinho Neto were contacted and we briefly visited the field.

Based on our preliminary trip, the National Geographic Society and the Petroleum Research Fund of the American Chemical Society funded expeditions in 2006 and 2007.

Discovery site in 2006

Discovery site of Angolasaurus in 1962

IEMBE (north of Luanda)90 million years old

Home of Angolasaurus

Drawing of original specimen, 1964

The best specimen, 2006

Ammonite in Iembe cliff

Angolasaurus before excavation

Excavation of front flipper of Angolasaurus(note ammonite lying next to fingers)

Shark Vertebrae, Iembe, 90 Million Years

The first dinosaur,a sauropod, found in Angola, at Iembe.

Excavation pit for front leg of sauropod dinosaur

Professor Jacobs (SMU) excavating arm bone of Angolan dinosaur

Unexcavated Turtle Skull

BENTIABA68 Ma, 15ºS

Each red point is a good fossil.

Terrestrial redbeds (80 million years) at base of Bentiaba section indicates deposition under arid, desert conditions.

Yellow marine strata overlie the terrestrial redbeds shown in photo at left. Black rock isvolcanic lava that flowed into the ancient sea. Mosasaurs, plesiosaurs, turtles, pterosaurs, and fish occur in the marine strata.

Stratigraphic Section at Bentiaba

Bentiaba (68 Ma)Plesiosaur paddle

Prognathodon kianda,a new mosasaur from Angola !!!

Shark teeth from Bentiaba.

Shark bite marks on mosasaur rib (right).

Ray teeth from Bentiaba. MANY TOP PREDATORS,PRODUCTIVE SEA

The abundance of top predators along the ancient coast of Angolademonstrates that the sea was productive, just as it is now.

However, offshore productivity is now caused by the Benguelacurrent, which is said to be only 6 million years old, not 90-66 million when the fossils were alive.

The explanation for ancient productivity lies in the Earth’s climatic zones coupled with continental drift of Africa.

This allows a better understanding of when petroleum source rocks might be generated in a given coastal area.

Figure 6-8Page 107

60ºN

30ºN

30ºS

60ºS

Cold deserts

Westerlies Forests

Hot desertsNortheast trades

ForestsEquator

Hot deserts

Forests

Southeast trades

Westerlies

Cold deserts

ATMOSPHERIC CIRCULATION AND

CLIMATE

The Namibe Desert has productive upwelling offshore that is caused by southeast trade winds blowing across the continent and pushing water away from shore, to be replaced by nutrientrich water from depth.)

Africa moved northward with continental drift, changing the position of upwelling relative to the continental margin and causing fossil localities (colored dots) to change latitude. Strongest upwelling now lies off Namibia (shaded), but in the past, strong upwelling lay off of northern Angola, causing the formation of petroleum source rocks there.

A 90 million year old forest (orange dot) is now fossil wood submerged from sea level rise at the mouth of the Orange River (underwater photos in center), in the Namibe Desert. The structure of the fossil wood (right) indicates that the forest grew originally in temperate climate, but its fossil remains moved north through geologic time because of continental drift into the desert zone of the Orange River Basin.

Pictures of submerged fossil logs

Desert

Temperate

I

O

B

M

L

DRIFT OF ANGOLAN FOSSIL LOCALITIES THROUGH NAMIBE DESERT LATITUDES (Graph of paleolatitude through time of fossil localities. Brown line at top represents Landana [L] and Malembe [M], Cabinda)

O Orange River B Bentiaba B Bentiaba I Iembe L,M

35 Million Year Old Rocks at Malembe, Cabinda (Site of Oldest Known Subsaharan Primate)

Plant-rich organic beds of Malembe (formed intropical latitudes) compared to sterile beds at CaboLedo, south of Luanda (formed in arid latituded).

Latitudinal Drift of Africa, Australia, and South America from Jurassic to Present

0-10-20-30-40-50-60-70-80-90-100-110-120-130-140-150-160-170

Age (170 Ma to present)

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

Rot

ated

Lat

itude

South America

AfricaAustralia

These graphs and the preceding photos demonstrate geologic conditionsfor upwelling productivity shifting along the coast as Africa moved norththrough time. The plot of latitude as a function of geologic time predicts the age of potential source rocks in southern continents.

Stacked rocks at Bentiaba allow the most precise determination of ancient shoreline possible.

Basalt at Bentiaba Demonstrates Shoreline Position(Lava at left flowed into shallow wet sand 68 million years ago; red baked zone under lava

at right shows flow over dry land; ancient shoreline lay between the two.)

Landward

Seaward

Mosasaurs and dinosaurs were supposedly driven extinct by the impact of a large asteroidwhich slammed into the sea near Mexico 66 million years ago.

The ocean wave caused by the asteroid impact struck the Angola coast and left its mark.

The effect of asteroid impact in Angola seen at the ancient shoreline south of Bentiaba.

WHEN DINOSAURS AND MOSASAURS WENT EXTINCT!

Our objectives are:

1. To continue this project with colleagues from UniversidadeAgostinho Neto University and other Angolan institutions;

2. To train Angolan student(s) in paleontology, geochemistry,or museum management at Southern Methodist University;

3. To obtain funding from the U.S. National Science Foundationfor laboratory and partial field costs to continue this project for the long term.

These objectives could be facilitated from the Angolan side if logistical in-kind support were provided (vehicles,accommodation, translators). Help will also be needed toidentify potential students.

Thank you from Angolasaurus(and SMU!)