A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the text, which is about dinosaur skeletons. It does not need another sentence for context. It does not start with a conjunction or use pronouns. It also does not use the definite article 'the' for a defined subject. Why other lines are not chosen? Paragraph 2 starts with 'Nevertheless', which is a conjunction, so it cannot be first. Paragraph 3 uses 'All eight', which refers back to something not yet mentioned, so it cannot be first. Paragraph 4 starts with 'Most come from', which also refers back to previous information. Paragraph 5 starts with 'Four of the species', which again refers back to something not yet introduced.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it provides specific details about the types of dinosaurs and their behavior. It wraps up the information by giving a clear picture of the dinosaurs mentioned in the previous paragraphs.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it uses the connector 'Nevertheless'. This shows that even though no complete skeletons have been found, palaeontologists can still identify types of dinosaurs. This is a logical flow of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically because it gives more information about the eight types of dinosaurs mentioned. It provides a broader context about the time period they lived in, which is a general statement that supports the previous paragraph.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it gives specific details about the time period of the dinosaurs. It narrows down the general information from Paragraph 3 to a more specific time frame, showing a logical order.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 follows Paragraph 4 because it introduces the types of dinosaurs that lived during the time mentioned. It shows a logical order by explaining what the dinosaurs did during that period.