The more examples you see, the better. The anteroseptal STEMI ECG example below is good enough to call a tombstone in lead V3. There is no lateral involvement here. Although not quite a tombstone ...

An anterior wall myocardial infarction may also be known as anterior wall MI (AWMI) or anterior ST segment elevation MI (anterior STEMI). When an AWMI extends to the septal and lateral regions as ...