And the dig goes on (Post for July 9th)

The mosasaur site has continued to yield many new bones. The most exciting parts to be revealed so far include a well-preserved articulated left mandible, missing the posterior part due to erosion. You will notice the teeth in the image below are not in place but have fallen out of their sockets. That is because Globidens phosphaticus, unlike other mosasaurs, never cement their teeth to the dentary, but instead maintain flexible periodontal ligaments through life, as we reported in our 2010 paper on this taxon (Polcyn et al., 2010).

Left mandible of Globidens phosphaticus. Copyright Projecto PaleoAngola.

A beautiful series of vertebrae, that in life would have been right in front of the fluke and downturned part of the tail, lie articulated in life-position, and was very exciting to uncover. Many other tail vertebrae can be seen disarticulated. We still have a large section of bone bed to uncover, so hoping for more great discoveries to come.

Above, Nemo using large rotohammer; below, tail vertebrae of Globidens phosphaticus. Copyright Projecto PaleoAngola.

Octávio and Louis paid a courtesy call on the local government administrators in Bentiaba and showed them the Sea Monsters power point. At every presentation, the urgency of protecting the fossil sites is emphasized.

Spellbound local administrators at Bentiaba leaning about Sea Monsters Unearthed and Projecto PaleoAngola.

Then they met up with our group of four students from the Universidade de Agostinho Neto in Luanda that have joined us for the remainder of the expedition. The students were given a quick tour of the geology in and around Bentiaba and were briefed on the objectives for this year’s field season. The second team also worked on measuring the stratigraphy and collected sediment samples.

The first stop was to see a plant: Welwitschia mirabilis, the iconic and defining plant of the Namibe Desert in Angola and Namibia. It grows nowhere else today, but fossil leaves have been found in the Early Cretaceous of Brazil from a time when Africa and South America were still connected and the South Atlantic Ocean had not formed.

Octávio showing geology students from Agostino Neto University Welwitshia mirabilis. Left to right: Isabel dos Santos (hidden by Octávio), Euridice Pacheco, Celso Riquenga, and Simã (Nimo) Ními. Welwitchia has only two broad straplike leaves that fray along the ground. The leaves of this specimen, like other Welwitschia plants in its neighborhood, are nibbled back nearly to the stem. This locality is about 20 kilometers north of Bentiaba, near Fael’s camp. So far as we are aware, this is the northernmost limit of Welwitschia in the world.
A geology lesson along the cliffs at Bentiaba.
The crew at the Globidens Quarry. From left to right: Octávio, Mike, Louis, Riquenga, Isabel, Alex, Miguel, Euridice, and Nemo.

After cleaning up the quarry and arriving back to camp, the team gave a presentation to our camp hosts and fellow researchers and students, covering the work Projecto PaleoAngola has done over the years, culminating with the Smithsonian exhibit. Everyone seemed to enjoy it and afterward, one of our hosts gratefully exclaimed that finally being able to understand the ancient history of this place was like “a light” being turned on for her. We couldn’t have asked for a more rewarding end to a hard workday.

Rapt attention during the Sea Monsters power point presentation in the dining hut of Fael’s camp, where we stay in the field. Our dome tents can be seen in the distance through the screening.

Polcyn, M.J., Jacobs, L.L., Schulp, A.S. and Mateus, O., 2010. The North African mosasaur Globidens phosphaticus from the Maastrichtian of Angola. Historical Biology22(1-3), pp.175-185.

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