( ( Based ( on ( ( many ( other lines ) ) ( of evidence ) ) ) ) ( , ( we ( already ( ( knew ( that ( ( modern tetrapods ) ( evolved ( from ( a ( fish ancestor ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (PP (VBN Based) (PP (IN on) (NP (NP (JJ many) (JJ other) (NNS lines)) (PP (IN of) (NP (NN evidence)))))) (, ,) (NP (PRP we)) (ADVP (RB already)) (VP (VBD knew) (SBAR (IN that) (S (NP (JJ modern) (NNS tetrapods)) (VP (VBD evolved) (PP (IN from) (NP (DT a) (NN fish) (NN ancestor))))))) (. .)))
Based on many other lines of evidence, we already knew that modern tetrapods evolved from a fish ancestor.
(ROOT (S (NP (NNS Caecillians)) (VP (VBD evolved) (PP (IN from) (NP (JJ tetrapod) (NNS ancestors)))) (. .)))