Based on prior knowledge, we can assume that individuals aged 65 and above are considered seniors. Therefore, we will classify individuals in the 'Senior' age group if their RIDAGEYR is greater than or equal to 65, and classify the rest as 'Adults'.

To analyze the relationship between the feature RIDAGEYR and the target variable, we need to examine the distribution of RIDAGEYR values for each target class.

Here is the dictionary with typical RIDAGEYR values for each target class:

```json
{
	"Adult": [20.5, 35.7, 45.2, 50.8, 63.4],
	"Senior": [70.1, 75.9, 80.3, 85.2, 91.5]
}
```

Please note that these values are just examples and should be replaced with actual values from the dataset. The values are provided as floats in a list format as requested.