whether tripitak talk about marananusati or maranassati?

I don't care whatever people think "is this wholesome is in Tipitaka or not?" because it's always truth whether "maraṇassatiṃ bhāveti" is an important meditation no matter whatever people said.

ekakanipāta,pāḷi 43 paṇṇe

maraṇasaññaṃ bhāveti… āhāre paṭikūlasaññaṃ bhāveti… sabbaloke anabhiratisaññaṃ [anabhiratasaññaṃ (sī. syā. kaṃ. pī.)] bhāveti… aniccasaññaṃ bhāveti… anicce dukkhasaññaṃ bhāveti… dukkhe anattasaññaṃ bhāveti… pahānasaññaṃ bhāveti… virāgasaññaṃ bhāveti… nirodhasaññaṃ bhāveti….

[463-472] aniccasaññaṃ bhāveti… anattasaññaṃ bhāveti… maraṇasaññaṃ bhāveti… āhāre paṭikūlasaññaṃ bhāveti… sabbaloke anabhiratisaññaṃ bhāveti… aṭṭhikasaññaṃ bhāveti… puḷavakasaññaṃ [puḷuvakasaññaṃ (ka.)] bhāveti… vinīlakasaññaṃ bhāveti… vicchiddakasaññaṃ bhāveti… uddhumātakasaññaṃ bhāveti….

[473-482] buddhānussatiṃ bhāveti… dhammānussatiṃ bhāveti… saṅghānussatiṃ bhāveti… sīlānussatiṃ bhāveti… cāgānussatiṃ bhāveti… devatānussatiṃ bhāveti… ānāpānassatiṃ bhāveti… maraṇassatiṃ bhāveti… kāyagatāsatiṃ bhāveti… upasamānussatiṃ bhāveti….

Upajjhatthana Sutta: Subjects for Contemplation

(Actually it's not often do, it is always doing continuously.)

"There are these five facts that one should reflect on often, whether one is a woman or a man, lay or ordained. Which five?

"'I am subject to aging, have not gone beyond aging.' This is the first fact that one should reflect on often, whether one is a woman or a man, lay or ordained.

"'I am subject to illness, have not gone beyond illness.' ...

"'I am subject to death, have not gone beyond death.' ...

"'I will grow different, separate from all that is dear and appealing to me.' ...

"'I am the owner of my actions,2 heir to my actions, born of my actions, related through my actions, and have my actions as my arbitrator. Whatever I do, for good or for evil, to that will I fall heir.' ...

"These are the five facts that one should reflect on often, whether one is a woman or a man, lay or ordained.

...

And much more Suttas.

Meditation basically into to stages

01.Samatha 02.Vidarshana[Vipassana]

To Investigate about this real world we need to acquire a Samadhi. For this purposes lord buddha taught us those meditation methods.
Lord buddha showed us 40 ways to conduct meditation and those 40 ways called "Sama Sathalis Karmasthana". Those who wanted to start meditaion, first need to identify him or herself. Their characters. Then accordingly they need to choose their Karmasthana.

Karmasthana basically works against their characteristics and bring them neutral or clam. Example: If you are an angered person you need to practise Metta Bhavana. if you are a lusty person you need to practise asubha bhavana. If you cannot figure out where you place yourself exactly start with Anapanasathi.

That is why we are advised to take Monks or Guru's guidance and advices before starting the meditation. To select suitable "Kamatana". Not only that while meditating you may be arising questions or points that need to sortout then and there and clear the mind about those questions. I am talking about the meditation that leads to Nibbana.

Those 40 methods are: These 40 classic and orthodox meditation subjects are:

I. The 10 Kasina exercises: Kasina = 'Entirety'. All 4 jhānas possible. 1: Earth kasina, 2: Water kasina, 3: Fire kasina, 4: Wind kasina, 5: Blue kasina, 6: Yellow kasina, 7: Red kasina, 8: White kasina, 9: Light or consciousness kasina, 10: Space kasina.

II. The 10 perceptions of disgust: asubha-sañña: 1st jhāna possible:

1. A swollen and bloated corpse,
2. a bluish livid corpse,
3. a rotting corpse,
4. a cut-up and split corpse,
5. a gnawed corpse,
6. a hacked corpse,
7. a spread scattered corpse,
8. a bloody corpse,
9. a corpse of maggots,
10. a skeleton.

III. The 10 contemplations: remembrances or recollections anussati:

1. On the Buddha,
2. The Dhamma,
3. The Noble Sangha community,
4. Morality,
5. Generosity,
6. Heavenly divine beings,
7. Death-Marananussathi, 7.1. To Learn More Click this Link, 7.2. More about Marana sathi, 7.3. How to Start Meditating on Death (A Guide for Beginners),
8. Body,
9. In-and-out-breathing: All 4 jhānas possible!,
10. Peace.

IV. The 4 divine abodes or infinite states: brahma-vihāra:

1. All-embracing friendliness = mettā,
2. Pity = karunā,
3. Mutual joy = muditā,
4. Equanimity = upekkhā, All 4 jhānas successively possible.

V. The 4 formless spheres arūpāyatana: based on the 4th jhāna:

1. The infinitude of space,
2. The infinitude of consciousness,
3. Empty nothingness,
4. Neither-perception-nor-non-perception.

VI. Perception of the loathsomeness of food āhāre patikkūla-saññā:

VII. Defining Analysis of the four great elements dhātu-vavatthāna:.

Now you know Where exactly Marananussathi Bhawana includes in Buddhism. Also, above articles I saw many sutta's mentioned about Marananussathi. Follow the links that you have provided so that you can learn more about meditaion.

May Triple Gem Bless You!!!

Yes Marananussathi is discussed in Tipitaka. Please correct me if I'm wrong, but Maranassathi and Marananussathi are same isn't it?

Please refer

1. KN 1 (Mahāniddesa - Aṭṭhakavagga -> 1. Kāmasuttaniddesa).

Buddhānussatiṁ bhāventopi vikkhambhanato kāme parivajjeti, dhammānussatiṁ bhāventopi …pe… saṅghānussatiṁ bhāventopi … sīlānussatiṁ bhāventopi … cāgānussatiṁ bhāventopi … devatānussatiṁ bhāventopi … ānāpānassatiṁ bhāventopi … Variant: ānāpānassatiṁ → ānāpānasatiṁ (bj); ānāpāṇassatiṁ (pts-vp-pli1)maraṇassatiṁ bhāventopi … kāyagatāsatiṁ bhāventopi … upasamānussatiṁ bhāventopi vikkhambhanato kāme parivajjeti.

Buddhānussatiṁ bhāventopi vikkhambhanato kāme parivajjeti, dhammānussatiṁ bhāventopi …pe… saṅghānussatiṁ bhāventopi … sīlānussatiṁ bhāventopi … cāgānussatiṁ bhāventopi … devatānussatiṁ bhāventopi … ānāpānassatiṁ bhāventopi … Variant: ānāpānassatiṁ → ānāpānasatiṁ (bj); ānāpāṇassatiṁ (pts-vp-pli1)maraṇassatiṁ bhāventopi … kāyagatāsatiṁ bhāventopi … upasamānussatiṁ bhāventopi vikkhambhanato kāme parivajjeti.

Also see,

2. AN8.73 Paṭhamamaraṇassatisutta

3. AN6.20 Dutiyamaraṇassatisutta