Sri Krishna says that he was Ushanas among seers in B.G.
वृष्णीनां वासुदेवोऽस्मि पाण्डवानां धनंजयः।
मुनीनामप्यहं व्यासः कवीनामुशना कविः।।10.37।।
Of the Vrsnis (the members of the Vrsni clan), I am the son of Vasudeva; of the sons of Pandu, Dhananjaya (Arjuna) [I am]; of the sages too, I am Vyasa; of the seers, the seer Usanas.
Sri Krishna also says he is Bhrigu among Maharshis.
महर्षीणां भृगुरहं गिरामस्म्येकमक्षरम्।
यज्ञानां जपयज्ञोऽस्मि स्थावराणां हिमालयः।।10.25।।
Of the great rishis, I am Bhrgu; of the words, I am the Single-syllable (Om); of the sacrifices [performed with external objects], I am the sacrifice of muttering prayer; of the immovables, I am the Himalayan range.
I found the following mantra from Rig Veda, which mentions Usana.(IX.87.3)
Rsi and Sage, the Champion of the people, cleft and sagacious, Usana in wisdom, He hath discovered even their hidden nature, the Cows' concealed and most mysterious title.
It was not Sri Krishna alone, who was greatest Yogi of his time, but even in Rig Veda, Indra stated that he was Usana.
अहम मनुर अभवं सूर्यश चाहं कक्षीवां रषिर अस्मि विप्रः |
अहं कुत्सम आर्जुनेयं नय ॠञ्जे ऽहं कविर उशना पश्यता मा ||
I was aforetime Manu, I was Sūrya: I am the sage Kakṣīvān, holy singer. Kutsa the son of Ārjuni I master. I am the sapient Uśanā behold me.
Now my question is what is the greatness of Ushanas?