The deepest roots of Mūrti worship can be traced to Śrautam. A few examples: 1. Physical characteristics of Devas in Ṛk-Sam̐hitā 2. Installation of a golden Puruṣa in the Agnicayana at base of Uttaravedi.++ See next tweet for one more example.
3. Varuṇa is expressly given the Jumbaka-Rūpa (a bald man with a “white” head & reddish-brown eyes) in Veda.
In the above three examples, you have the prototypes of all the memes that make up Mūrti-Yajana (worship) as we know today.
Example 1: Indra with golden hair, etc; Rudra with turban, etc - The basic idea of gods having forms is right there in Ṛk-Sam̐hitā.
Example 2: The Golden Puruṣa installed under the Uttaravedī altar is Prajāpati himself. Here, you have the idea of a anthropomorphic representation of a deity.
Example 3: Now, Mūrti-Pūjā is not limited to forms made from insentient materials (metal, wood, etc) but can include human/animal forms as well. Here, offerings to Varuṇa are made on the head of a man with particular physical characteristics.
Thus, the essential memes making up Mūrti worship are all there in the Veda in sone form.