Forming a notochord like those still found in some of today's jawless fish.

形成索，就像今天仍然在一些无颌鱼中发现的索一样。

Perhaps the chordate crowd, with their notochords, segmented muscles and big bony skeletons.

或许是索，有索，分节肌肉和干瘪大骨架。

And the rod down its back was a notochord, an early precursor of the vertebral column seen in vertebrates.

它背上的杆是索，是椎柱的早期前身。

For one thing, the white lines found on some of those fossils go past the eyestalks where true notochord would end.

一方面，在其中一些化石上发现的白线越过眼柄，而真正的索应该在眼柄处结束。