PRELIMINARY INFORMATION ON A TITANOSAURID AXIS FROM MARÍLIA FORMATION (MAASTRICHTIAN AGE), MINAS GERAIS STATE, BRAZIL

The specimen was collected by L.I. Price, at a quarry known as "Mombuca", near the municipality of Peirópolis. The outcrop corresponds to the Marilia Formation (Maastrichtian Age, Bauru Basin). This specimen was in the collection of DNPM together with specimen known as "Series A" (MCT 1487-R). The specimen corresponds to a titanosaurid axis. The axis is a small but complex bone, the centrum is relatively elongated, with the length of the centrum being more than twice the height. The outline of the centrum is rectangular. The neural arch is fused to the centrum, being high. The axis presents the odontoid process fused in the anterior margin of the intercentrum. The parapophyses are massive robust projection, positioned in the most anterior portion of the centrum. In lateral view, the centrum is slightly curved downwards, with strong marked margins. There is a pleurocoel located near the parapophyses. In ventral view, there is an anteroposterior low, but laterally expanded ridge starting near the parapophyses, extending up to the middle length of the vertebra, separating its left and right side. In each side there are two pneumatic foramens located anteriorly, between the parapophyses. The first pair of foramen are shallower than the posterior ones. The cotyle is deep. The reduced prezygapophys is a small, tab like structure that do not project forward from the neural arch (preserved only on the righ side). Both postzygapophyses are short and robust, the right one is more preserved, showing a portion of the articular surface. The centropostzygapophyseal laminae are very thin, flat laminae which gives the neural channel a squared appearance. The intrapostzygapophyseal lamina is located considerable anteriorly. These lamina are not well developed, and forms an acute "V" shaped angle instead of more common "U" shaped. The overall shape of this specimen resembles the condition seen in "Series A", differing mostly by the smaller size and the presence of the odontoid process. This specimen was kept in the Museu Nacional for study during the fire incident, and its condition is unknown. Important information regarding this specimen can also be recover by the CT-Scan previously performed. [FAPERJ -E-26/200.118/2018].