The writer should not delete this sentence because it would make the meaning of anomaly clearer to the reader.
Wat should be done?
The writer is not meant to delete the sentence because it clarifies the meaning of the word, an anomaly. When a reader who may not have a wide vocabulary is reading a text, they may not know the meaning of certain words. The best way to carry them along is to add further meaning to the passage by means of explanations such as the one above.
So, the reader better understands the meaning of the word, anomaly because of the description given.