Homotherium serum, scimitar-toothed cat. Computer illustration and photo-reconstruction of the scimitar cat Homotherium serum. Homotherium serum occurred in North America from the late Pliocene until the late Pleistocene. Remains have been found at various sites between Alaska and Texas. The scimitar cat is about the size of a lion, but lighter in body. The scimitar cat (Homotherium serum) was a smaller and lesser known cousin of the more famous sabre-toothed cat (Smilodon fatalis). This species enjoyed one of the largest geographic distributions of any known cat living or extinct.