Which of the following was a feature of civilizations in Mesoamerica during the classical era that was not shared by civilizations in South America at the time?

To answer this question, we first need to understand what the classical era refers to. The classical era in Mesoamerica is typically considered to be from around 250 to 900 AD, while in South America it varies depending on the civilization.

Next, we need to know what features are being referred to. This could include things like political systems, religious beliefs, architectural styles, agricultural practices, etc.

One feature that was present in Mesoamerican civilizations during the classical era but not in South American civilizations was the development of a complex writing system. The Maya, for example, had a fully developed writing system, while civilizations in South America, such as the Moche, did not.

Another feature could be the construction of large-scale ceremonial centers. While both Mesoamerican and South American civilizations built impressive structures, the scale and complexity of sites like Teotihuacan in Mesoamerica were not matched in South America during the classical era.

However, it's important to note that this is a generalization and there were likely exceptions and variations within each civilization.