Vertebrates generally have all of the following characteristics, except

Options

A. Cephalization
B. Spinal columns
C. A chitinous endoskeleton
D. A closed circulatory system

Answer

To determine which characteristic is not typically found in vertebrates, we can analyze the provided options one by one:

1. **Herculation (Formation of Brain)**: Vertebrates possess a well-developed brain, which is a defining characteristic of this group. This option is true for vertebrates.

2. **Vertebral Column (Spinal Cord)**: Vertebrates are named for their vertebral column, or backbone, which protects the spinal cord. This is also a characteristic of vertebrates.

3. **Chitinous Endoskeleton**: Vertebrates do not have a chitinous endoskeleton. Instead, their endoskeleton is primarily composed of bone or cartilage. Chitinous structures are found in invertebrates, such as insects. Therefore, this option is not a characteristic of vertebrates.

4. **Closed Circulatory System**: Vertebrates have a closed circulatory system, which efficiently separates oxygenated and deoxygenated blood. This is a true characteristic of vertebrates.

Based on this analysis, the characteristic that is not found in vertebrates is the **chitinous endoskeleton**.

### Step-by-Step Solution:
1. **Identify the characteristics of vertebrates**: Understand the common traits that define vertebrates.
2. **Analyze each option**: Go through each provided option and determine if it is a characteristic of vertebrates.
3. **Eliminate true characteristics**: Remove options that are indeed characteristics of vertebrates.
4. **Identify the exception**: The option that does not fit the characteristics of vertebrates is the answer.