The spikes

The last things you need to crochet are Fred's five spikes. Grab the yellow yarn and make a magic loop with 4 single crochet stitches in it. By the end of this, you'll be an expert at magic loops.

Round 1:
4 sc in magic loop
Round 2:
[sc, inc] x 2 (6)

Fasten off invisibly and leave a long tail. Use the tail to sew the
corresponding spike to the middle of the dinosaur’s back. Attach the spike at
the tip of the tail first, and work your way up. There should be 1-2 rounds in
between each spike. 

dinosaur back with spikes