You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Mesozoic

Context:
Recent research indicates that the specialized animals that formed complex ecosystems, with high biodiversity, complex food webs and a variety of niches, took much longer to reestablish, recovery did not begin until the start of the mid-Triassic, 4M to 6M years after the extinction and was not complete until 30M years after the Permian–Triassic extinction event. Animal life was then dominated by various archosaurian reptiles: dinosaurs, pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs.

Question:
What type of animals took longer to reestablish?

specialized animals