Answer:
The meteorite caused tectonic plates to move apart, causing volcanoes to erupt. The volcanoes erupting caused large clouds of ash to mix with the dust cloud. This large cloud of dust and ash covered the entire planet and just kept getting thicker due to the volcanoes erupting for days at a time. Once the cloud had dissolved completely, the plants had all died due to the very little amount of sunlight that reached the Earth. Without plants, the animals started to die off too. By the time the plants started to grow back, they were all already dead.