First, the horsemen brought out a teaser horse.
( First ( , ( ( the horsemen ) ( ( ( brought out ) ( a ( teaser horse ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB First)) (, ,) (NP (DT the) (NN horsemen)) (VP (VBD brought) (PRT (RP out)) (NP (DT a) (NN teaser) (NN horse))) (. .)))
First, the horsemen brought out a teaser horse because the main horse has not arrived yet.
( First ( , ( ( the horsemen ) ( ( ( ( brought out ) ( a ( teaser horse ) ) ) ( because ( ( the ( main horse ) ) ( ( has not ) ( arrived yet ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB First)) (, ,) (NP (DT the) (NN horsemen)) (VP (VBD brought) (PRT (RP out)) (NP (DT a) (NN teaser) (NN horse)) (SBAR (IN because) (S (NP (DT the) (JJ main) (NN horse)) (VP (VBZ has) (RB not) (VP (VBN arrived) (ADVP (RB yet))))))) (. .)))