( ( Unlike insects ) ( , ( spiders ( ( ( have ( ( an endoskeleton ) ( in addition ) ) ) ( to ( their exoskeleton ) ) ) . ) ) ) )
(ROOT (S (PP (IN Unlike) (NP (NNS insects))) (, ,) (NP (NNS spiders)) (VP (VBP have) (NP (NP (DT an) (NN endoskeleton)) (PP (IN in) (NP (NN addition)))) (PP (TO to) (NP (PRP$ their) (NN exoskeleton)))) (. .)))
Unlike insects, spiders have an endoskeleton in addition to their exoskeleton.
(ROOT (S (NP (NNS Humans)) (VP (VBP possess) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN endoskeleton))) (. .)))