Learn Spanish (Latin America): El animal vertebrado solía dormir durante el día. - The vertebrate animal used to sleep during the day.

No. Vertebrado is a relational adjective, meaning it classifies the noun into a specific scientific category (a vertebrate) rather than describing a subjective quality. In Spanish, relational adjectives must always go directly after the noun they modify.

Can I use an intensifier here, like saying the animal was muy vertebrado?

Grammatically, no. Because vertebrado is a relational adjective that puts the animal into a strict category, it is treated as an absolute (an animal either has a spine or it does not). You cannot use intensifiers like muy or bastante with this class of adjectives.

Why use solía dormir instead of just the imperfect tense dormía?

Both are correct for past habits. Dormía translates to 'slept' or 'was sleeping', which often implies 'used to sleep' in context. However, using the imperfect of soler (solía) plus the infinitive dormir explicitly highlights that this was a routine or habitual action.

As a quick refresher, why is it el día if the word ends in -a?