Preheat oven to 375°F. Line a baking sheet with parchment paper. Coarsely grate 1 1/2 onions; cut six 1/2-inch triangles (for teeth) from the remaining onion; set aside. In bowl, mix together ground beef, breadcrumbs, egg, grated onion, 1/4 cup tomato sauce, 1/4 cup BBQ sauce, oil, Worcestershire sauce, 2 Tbsp. water, salt and pepper.
Place meat mixture on lined baking sheet. Shape into an oval loaf, about 9’’ long and 5’’ across at its widest. The loaf should be almost as high as it is wide. At one end of loaf, use fingers to make two indents to hold olive halves for eyes (don’t add olive halves until after baking). Insert onion triangles in a row along “mouth” to resemble craggy teeth.
Bake 30 minutes. Brush with remaining BBQ sauce and bake another 20 minutes. until golden brown and instant-read thermometer inserted in centre registers 165°F. Let rest 15 minutes; transfer to serving platter.
Meanwhile, bring remaining tomato sauce in small saucepan to a simmer over medium heat.
Arrange olive halves in eye indents. Place carrot or celery sticks at sides of loaf for “legs”. Insert 2 rows of tortilla chips along the top of the loaf as a dinosaur-like spiky back. Serve slices with Gory Tomato Sauce on the side.