For example, several of the Dravidian proposals for Indus script equate the "fish" sign with "star", as the proponents consider the words for 'fish' and 'star' as homophones in Proto-Dravidian. I had earlier argued with Parpola (who is a member of this list) and others on the folly of equating mīn- 'fish' [DEDR 4885] with miṇ-/min-(?) 'to glitter, star, sky' [DEDR 4876]. I believe these two entries are unrelated etymologically. If you look at the entries for DEDR 4876, you notice a retroflex ṇ in many entries, which is somehow absent from Tamil-Malayalam. De-retroflexion of a nasal is common in the South-Central, Central and North Dravidian languages. That means, an absence of a retroflex in those languages is not surprising, but the presence of a retroflex consonant in languages across subgroups certainly adds credence to its presence in the proto-language.
4876 Ta. miṉ flash, glitter, lightning; miṉmiṉi firefly; miṉṉu (miṉṉi-) to emit lightning, shine, glitter; miṉṉal lightning; bright coin; miṉuṅku (miṉuṅki-) to glitter, shine, appear bright; miṉukku (miṉukki-) to polish, brighten, beautify, make a display; miṉukkam, miṉukkal polish, brightness, excellence, showiness, show; mīṉ star. Ma. minnuka to flash, shine; minnal lightning; minni shining; a gem in ear-rings; minnikka to cause to flash or shine; minnulightning; minukka to be fine, glitter; minukkuka to polish, varnish, make glitter; minukkam shining, polish; minuṅṅuka to glitter; minuppu sparkling; mīn star. Ko. minc- (minc-) to flash, glitter, be dazzling, lighten; mi·n star. To.mic- (mi&cangle;-) to flash, lighten; mic lightning (in songs); mi·n star. Ka. miṇa glittering, sparkling; miṇaku, miṇuku to glitter; n. glitter; minu, mini sparkling, shining; minuku, minugu to shine, glitter; n. lustre, etc.; miñcu to shine, be bright, sparkle, glitter, flash, lighten; n. shine, lustre, brightness, glitter, lightning; mīn star. Koḍ. minn- (minni-) to lighten, flicker. Tu. miṇimiṇi twinkling, glistening, dimly shining; meṇů glitter, sparkle; miṇuku, meṇaků, meṇuku sparkling; miṇ(u)kuni, meṇ(ů)kuni, minukuni, meñcuni, miñcuni to shine, sparkle, glitter; meñci brightness, lightning; (B-K.) meṇkoḷi, menkōri glowworm. Te. miṇuku to glimmer, sparkle; n. glimmer, glimmering, sparkling; miṇũgu, miṇũguṟu, miḍũgu, miḍũguṟu spark of fire, firefly; min(u)ku twinkling, twinkle, glitter, flash, ray of light; (K. also) vb. to glitter, shine; minuku-minukum-anu, minukkuranu to twinkle; mincu a flash of lightning, shining, brilliancy; (K. also) vb. to shine as lightning, shine; minna a gem; minamina glitter, shining. Pa. minnal spark. Ga. (S.3) munake firefly. Go. (Tr.) mīnkō the stars which a stunned, dazed, or liverish man sees; (W. Ph.) minko, (Mu. Ko.) miṛko firefly; (Mu.) miṛkom, (M.) miṛko, (L.) miḍkos star; (Ma.) minˀkonj(i) (pl. minˀkosku) star, firefly (Voc. 2842); (Tr.) miḍstānā, (W.) mirsālnā, (M.) miṛkānā, (Ph.) mirsīlnā, mirsīltānā to flash, of lightning; (SR.) miḍcānā to flash; (A.) miṛc-, (Ma.) miṛs- to lighten (Voc. 2844); (ASu.) miṛc- to glitter; miṛcval lightning; (L.) mīḍsā, mīrcā id.; (LuS.) meershinta to glitter; meersheetatta lightning; (Mu.) mirŋgul, (Ma.) miṛŋgor̥spark (Voc. 2837); (ASu.) minṅūṛ id. Konḍa (BB) mirs- to lighten. Kuwi (Su.) mṇih- (mṇist-), miṇs- to lighten; (Isr.) mṇīh- (mṇīst-) id., glitter; mṇispu lightening; (S.) mirsi mannai to scintillate; mrih'nai to sparkle; (Mah.) miṇig-to shine. Kur. bīnkō star; bincō firefly. Malt. bínḍke star.
Similarly, Parpola says the following in his recent book:
"The Dravidian languages appear to have spread to central and southern India from the area of the Indus Valley. Copper Age cultures of the Deccan, which derive from the Early and Mature Harappan cultures of the Greater Indus Valley, spread farming and animal husbandry to central and southern India, in place of hunter-gathering" (Parpola, Asko (2015). The Roots of Hinduism: The Early Aryans and the Indus Civilization. Oxford University Press).
If Parpola believes that the Dravidian languages moved recently into central and southern India, then, he must agree that they haven't moved into "empty" area. We know there have been Paleolithic population living in South and Central India for at least 20,000 years. Then, there must have been a Dravidian colonization of South India where the pre-existing hunter-gatherer population have gone through acculturation and language-shift. Then, the Peninsular Dravidian langugaes must have acquired several non-Dravidian features (perhaps some of them are common across Indian linguistic area) through the influence of the languages of the HG (hunter-gatherer) population. That means, it is possible that several archaic features found in Tamil are in fact the archaic features of the aboriginal languages. As Herman Tieken had suggested earlier, Tamil cannot be the language of the southernmost region of Dravidian migration, and at the same time be the most conservative Dravidian language.
Furthermore, Parpola uses Tamil-based reconstructions to argue Dravidian roots for words with voiced consonants such as gardabha, bhekuri/ bekuri etc. without convincingly explanation for the word-initial voiced consonant in such wide variety of languages. The same Tamil-centric argument is made for kiyāmbu without explaining their presence in several Indian languages including East-Indian languages such as Assamese, Bengali and Oriya ( CDIAL 3465 kēmuka m. ʻ Costus speciosus ʼ lex., ʻ Colocasia antiquorum ʼ Bhpr. [Cf. kēvuka -- m. Car., kēcuka -- m. Suśr., kacu -- m., kacvī -- f. lex., kēlūṭa -- m. Npr., also ʻ a kind of potherb ʼ Car.: ← Drav. EWA i 266] B. kẽu ʻ Costus speciosus ʼ, Or. kaükaüā, H. keũā, keuā m. kēmbuka -- see kr̥muká -- .2609 kacu f. ʻ the esculent root of Arum colocasia. ʼ [Cf kacvī --f., kēcuka -- m. ʻ Colocasia antiquorum ʼ, kēmuka -- ] A. kasu, B. kacu, H. kacū, kaccū). He uses palatalization rule to explain kiyāmbu > cēmpu in Tamil, but by the same token he doesn't explain why kinnara doesn't become cinnara in Tamil.