作文:恐龙不migrate
1 one hundred million year ago wammer 夏天有时候极昼 储存的nutrient可以让死了的vegetation维持恐龙的生活
2 living in herds does not mean migration have other reasons extra protect from predator Roosevelt elk living in herds 但不迁徙
3 adults可能完成迁徙 但是juvenile 不行 整个herd会被拖累 完不成
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