An awesome 500+ page book about tortoise brooches and chain ornaments among the Livs of the Daugava in Late Iron Age Latvia. Here is a summary in English: http://www.docstoc.com/docs/70993239/Roberts-Spir-is-10th-13th-Century-Daugava-Liv-Pectoral-Chain. They are usually not difficult to distinguish from Norse tortoise brooches.
Late Iron Age Latgallian/latgaļu (?) grave goods from Lubānas Līčgali in Latvia. Burial Nr. 2. From "Finds of 'Smolensk' Type Zoomorphic Pendants on the Territory of Latvia and a New Interpretation" by Roberts Spirģis, https://www.academia.edu/19754362/Par_piekari%C5%86iem_-_zirdzi%C5%86iem_. Image enhanced by Balticsmith.
Owl fibula. Latgallian/Latgaļu. Latvia. Late Iron Age ca. 800 C.E. Owl fibulae were made only by the Baltic chiefdoms of the Latgaļi, Kurši and Zemgaļi. This one is now on exhibit at Latvian National History Museum in Rīga.