quinta-feira, julho 25, 2013

Expedição PaleoAngola: Blog

Aqui replico o blog da expedição PaleoAngola, disponível em http://www.paleolabs.org/paleoangola/field-blog:

Benguela Area Part 1
Near Benguela, there are extensive outcrops of red beds of silt, mud, and sandstones that are mapped as Albian in age. These red rocks show cross-bedding, bioturbation, and tree trunks that indicate that are terrestrial deposits, and therefore a good candidate for yielding  dinosaur bones. Moreover, we collected a few dinosaur bone fragments from equivalent beds in the Namibe region.

But reality is not always as we wish: a lot of walking... we found no vertebrate fossils. The most significant finding were some beautiful gymnosperm tree trunks.

The Upper Cretaceous marine beds were more productive, and we found many invertebrates, shark teeth, and some marine reptiles pieces, but mostly fragments. These finds are good for building the record, but we keep looking for new localities and fossils that can tell much more about evolution of vertebrates in Angola.

Field Blog 2013 - July 22

On July 16th, Louis Jacobs, Ana Marques, and John Graf flew up to Cabinda. Cabinda is a province to the north separated from the main country by the Republic of Congo.
From July 17th to July 20th, we prospected four beaches which had outcroppings that were of more recent ages. For the last four years, members of Project PaleoAngola have collected samples and measured sections at these localities for the purposes of determining the faunal assemblage of these outcrops and determining the ages of the rocks (something that had not previously been accomplished).
During these four days, we found two new localities that were fossil rich. From these localities, we were able to recover the same types of fossils found at the other localities along with a crocodile genus not described from this area before and an Arsinoitherium tooth.
Arsinoitheres are hippo-like mammals with two large tusks forming a V at the end of their snouts that lived during the Late Eocene and Early Oligocene.

These new fossils will add to the already rich fossil faunal assemblage found in Cabinda and will help narrow down the age of the rocks that they were discovered in.

On July 21st, we flew back to Luanda. On July 22nd, we flew down to Benguela to rejoin Michael and Octavio for the rest of the field season.

Field Blog 2013 - July 18

Malanje Trip

Octávio Mateus and Michael Polcyn drove to the Malange area while Louis Jacobs, John Graf, and Ana Marques went to Cabinda. In Malange (also spelled Malanje) and Lunda Norte provinces are in the north central part of the country and previous reports in Baixa de Cassange have shown a rich fauna of Triassic fossil fishes. These areas haven't been visited by paleontologists since the 1960's so we decided to give it a try.

We arrived to Malange on the evening of the 16th and met with our friend Pedro Vaz Pinto, a biologist that studies the giant sable, the Palanca-Negra-Gigante, the national symbol of Angola.  He has been capturing sables to fit them with radio tracking collars and told us that while they were darting a sable from a helicopter that day, a large male lion tried to take the sable. Fortunately the helicopter scared the lion away and the sable was safely collared. This sighting is extremely significant, being the first large predator in the area since the war ended.

Yesterday (the 17th) we drove to Xá-Muteba (Lunda Norte), the closest town to the Triassic fossil localities. The local authorities alerted us about the possible presence of landmines in the area we wanted to visit, so we met the de-mining team who informed us that the area surrounding the fossiliferous sites has not been completely cleared, so we headed back to Malanje to regroup and plan for the next day.

Today (the 18th) we decide to see the continental Cretaceous formations near Kiwapa Mzoji (former Brito Godins). There are good rock exposures along the  road cuts as the road expansion works progresses. The rocks are a varved mudstone and sandstone with some ripple-marks.... and no fossils. Although we were not able to find any fossils on this leg of the expedition, we did learn a lot about the area, the people and the rocks. In a few years, we expect the mines will be cleared and we will be able to go tot he Triassic localites. Tomorrow, we head back to the coast and plan to base in the port town of Benguela.

Field Blog 2013- July 16

The team met in Luanda on the 12th and after gathering the proper permits, and getting the vehicles and supplies organized, we set out for the localities in the north around the village of Iembe.  This locality has thus far yielded 4 holotypes; Angolasaurus bocagei, Tylosaurus iembeensis,  Angolachelys mbaxi, and Angolatitan adamastor.
Our goals this year for the Iembe locality were threefold. First, we needed to collect fossil molluscs for stable carbon isotope analysis to build a chemostratigraphy of the area which we will compare with the global record to provided better age control for the fossils we have recovered from the site. Second, we needed to revisit previous dig sites to see if any additional material had weathered out of the outcrops, and third, we wanted to prospect for new localities in the area.
We accomplished all of our goals and were especially excited to find a new productive locality to the north of the outcrops that had yielded our previous finds in the area. We found fragmentary material including a disarticulated turtle carpace, plesiosaur limb material, and a disarticulated mosasaur that appears to be Angolasaurus. We collected the plesiosaur limb and Angolasaurus material. Judging from the associated fish and molluscs, we believe this new locality is about the same horizon as the type locality of Angolasaurus and Angolatitan.
We returned to Luanda on the 15th to begin the next leg of the expedition.

1 comentário:

MauFeitio disse...

Ai a inveja dessa viagem é grande :)