First of all, I would like to ask you a question. Do you know what's the purpose of Bible? I have quickly quoted some verses below from the Bible for you to understand. The purpose of Bible is to let us understand the love of God, particularly how Jesus died for us to give us the eternal life.
In fact, Bible is NOT an encyclopeida. So, NOT EVERY DETAILS is covered in the Bible. In Genesis, it said that 創 世 紀1:25 於 是 神 造 出 野 獸 、 各 從 其 類 . 牲 畜 、 各 從 其 類 . 地 上 一 切 昆 蟲 、 各 從 其 類 . 神 看 著 是 好 的 。
Yes, I agree that it didn't mention 恐龍, but did it mention 松鼠? 紅衫魚? .....there are so so so many different types of animals and insects in the world. Yet, Bible is not an encyclopeida and so it doesn't record every details but just show you the key points, that is --- 神 造 出 野 獸. Remeber that the purpose of Bible (as mentioned in the Bible not I said) is to give you the wisdom to know more about the love of God, how to believe in HIM and how we could be saved by HIM.
I highly appreciate that you could keep understanding about God so that you could experience his love and be his son or daughter one day.