EXHIBIT 10.2

THIS NOTE HAS NOT BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES
ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE
SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL TO THE TRANSFEROR TO
SUCH EFFECT. SUCH SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE
MARGIN ACCOUNT WITH A REGISTERED BROKER-DEALER OR OTHER LOAN WITH A FINANCIAL
INSTITUTION THAT IS AN “ACCREDITED INVESTOR” AS DEFINED IN RULE 501(a) UNDER THE
SECURITIES ACT.

THIS NOTE DOES NOT REQUIRE PHYSICAL SURRENDER OF THIS NOTE IN THE EVENT OF A
PARTIAL REDEMPTION OR REPAYMENT. AS A RESULT, FOLLOWING ANY REDEMPTION OR
REPAYMENT OF ANY PORTION OF THIS NOTE, THE OUTSTANDING PRINCIPAL AMOUNT
REPRESENTED BY THIS NOTE MAY BE LESS THAN THE PRINCIPAL AMOUNT SET FORTH BELOW.

SENIOR SECURED NOTE DUE 2008

OF

TATONKA OIL AND GAS COMPANY, INC.

Note No.: 1        Original Principal Amount:  $200,000.00  Issuance Date: 
October 5, 2007             

     FOR VALUE RECEIVED, TATONKA OIL AND GAS COMPANY, INC. (the “Company”)
hereby promises to pay to or upon the order of Energy Capital Solutions, L.P. or
its registered assigns or successors-in-interest (the “Holder”) the principal
sum of Two Hundred Thousand Dollars ($200,000.00), together with all accrued but
unpaid interest thereon, if any, on the Final Maturity Date. Interest on the
unpaid principal balance hereof shall initially accrue at the rate of 15% per
annum, subject to adjustment as set forth herein (the “Interest Rate”), from the
date of original issuance hereof (the “Issuance Date”) until all amounts under
this Note have been paid in full in cash. Interest on this Note shall accrue
daily commencing on the Issuance Date, shall be compounded quarterly and shall
be computed on the basis of a 365/366-day year and actual days elapsed and shall
be payable in accordance with Section 2 hereof. Notwithstanding anything
contained herein, this Note shall bear interest on the outstanding

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Principal Amount from and after the occurrence and during the continuance of an
Event of Default, at the rate (the “Default Rate”) equal to two percent (2%) per
annum above the then applicable Interest Rate. Unless otherwise agreed or
required by applicable law, payments will be applied first to any unpaid
collection costs, then to unpaid interest and fees and any remaining amount to
unpaid principal.

                All payments of principal of and interest on this Note shall be
made in lawful money of the United States of America by wire transfer of
immediately available funds to such account as the Holder may from time to time
designate by written notice in accordance with the provisions of this Note. This
Note may not be prepaid in whole or in part except as specifically provided
herein. Whenever any amount expressed to be due by the terms of this Note is due
on any day which is not a Business Day, the same shall instead be due on the
next succeeding day which is a Business Day and such extension shall be taken
into account in determining the amount of interest accrued on this Note.

                The indebtedness evidenced by this Note is senior to all other
current and future indebtedness of the Company. Payment of the indebtedness
evidenced by this Note is (i) secured by all of the properties and assets of the
Company and Guarantor pursuant to that certain Security Agreement, dated as of
October 5, 2007, by and between the Company, Guarantor and Energy Capital
Solutions, L.P., as Collateral Agent for the Purchasers (the “Security
Agreement”) and (ii) guaranteed by the Guarantor pursuant to that certain
Guaranty, dated as of October 5, 2007, executed by Guarantor for the benefit of
the Purchasers.

                The following terms and conditions shall apply to this Note:

   Section 1. Definitions.

                (a) Capitalized terms used herein and not otherwise defined
herein shall have the meanings set forth in the Purchase Agreement.

                (b) For purposes hereof the following terms shall have the
meanings ascribed to them below:

                “Acceleration Date” shall have the meaning provided in Section
4(b).

                “Bankruptcy Event” means any of the following events: (a) the
Company or any material subsidiary commences a case or other proceeding under
any bankruptcy, reorganization, arrangement, adjustment of debt, relief of
debtors, dissolution, insolvency or liquidation or similar law of any
jurisdiction relating to the Company or any material subsidiary thereof; (b)
there is commenced against the Company or any material subsidiary any such case
or proceeding that is not dismissed within 60 days after commencement; (c) the
Company or any material subsidiary thereof is adjudicated insolvent or bankrupt
or any order of relief or other order approving any such case or proceeding is
entered; (d) the Company or any material subsidiary suffers any appointment of
any trustee, custodian or the like for it or any substantial part of its
property that is not discharged or stayed within 60 days; (e) the Company or any
material subsidiary makes a general assignment for the benefit of creditors; (f)
the Company or any material subsidiary fails to pay, states that it is unable to
pay, or is unable to pay, its debts (excluding those reasonably disputed in good
faith by the Company in the case of failure to pay

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and for which it has reserves on its books and financial statements) generally
as they become due; (g) the Company or any material subsidiary calls a meeting
of its creditors with a view to arranging a composition, adjustment or
restructuring of its debts; or (h) the Company or any material subsidiary, by
any act or failure to act, expressly indicates its consent to, approval of or
acquiescence in any of the foregoing or takes any corporate or other action for
the purpose of effecting any of the foregoing.

                “Board of Directors” means the Company’s board of directors.

                 “Cash” or “cash” means at any time such coin or currency of the
United States of America as shall at such time be legal tender for the payment
of public and private debts.

                “Change in Control Transaction” will be deemed to exist if (i)
there occurs any consolidation, merger, amalgamation or other business
combination of the Company with or into any other corporation or other entity or
person (whether or not the Company is the surviving corporation), or any other
corporate reorganization or transaction or series of related transactions in
which in any of such events the persons who are holders of the voting stock of
the Company immediately prior to such event cease to own more than 50% of the
voting stock, or corresponding voting equity interests, of the surviving
corporation or other entity immediately after such event (including without
limitation any “going private” transaction under Rule 13e-3 promulgated pursuant
to the Exchange Act or tender offer by the Company under Rule 13e-4 promulgated
pursuant to the Exchange Act for 20% or more of the Company’s Common Stock),
(ii) any person (as defined in Section 13(d) of the Exchange Act), together with
its affiliates and associates (as such terms are defined in Rule 405 under the
Securities Act), beneficially owns or is deemed to beneficially own (as
described in Rule 13d-3 under the Exchange Act without regard to the 60-day
exercise period) 50% or more of the voting power of the Company’s voting stock
or corresponding voting securities, (iii) there is a replacement of more than
one-half of the members of the Board of Directors which is not approved by a
majority of those individuals who are either members of the Board of Directors
on the date thereof or individuals approved by a majority of such members or
(iv) in one or a series of related transactions, there is a sale or transfer of
all or substantially all of the assets of the Company, determined on a
consolidated basis.

                “Event of Default” shall have the meaning provided in Section
4(a).

                “Exchange Act” means the Securities Exchange Act of 1934, as
amended.

                “Final Maturity Date” means the later of (a) the Initial
Maturity Date, or (b) the date that the Company elects to extend the term of
this Note pursuant to, and in accordance with, the provisions of Section 2(d).

                “Force Majeure Event” means an event or circumstance that
prevents the Company from performing its obligations under this Note or that
prevents an act or event required hereunder from happening or occurring
(including, without limitation, an act of God, war, insurrection, riot, nuclear
disaster, labor strike or threat of violence, labor and material shortage, fire,
explosion, flood, river freeze-up, breakdown or damage to wells, plant,
equipment, or facilities (including a forced outage or an extension of a
scheduled outage of equipment or

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facilities to make repairs to avoid breakdowns thereof or damage thereto),
interruption to or slowdown in transportation, railcar shortage, barge shortage,
embargo, order, or act of civil or military authority, law, regulation, or
administrative ruling, or total or partial interruption of the Company’s
operations which are due to any enforcement action or other administrative or
judicial action arising from an environmental law or regulation), but in any
case which is not within the reasonable control of, or the result of the
negligence of, the Company, and which by the exercise of due diligence, the
Company is unable to overcome or avoid or cause to be avoided or is unable in
good faith to obtain a substitute acceptable to the Holder therefor.

                 “Guarantor” means Tatonka Oil and Gas, Inc., the parent
corporation of the Company.

                “Initial Maturity Date” means the earlier of (i) the day that is
the thirtieth (30th) day following the consummation of the sale of any equity or
debt securities by the Company (other than the Securities contemplated by the
Purchase Agreement) or (ii) one hundred twentieth (120th) day immediately
following the Issuance Date.

                “Principal Amount” means at any time the sum of (i) the
outstanding principal amount of this Note at such time, and (ii) any default
payments owing at such time to the Holder under the Transaction Documents but
not theretofore paid or added to the Principal Amount.

                “Purchase Agreement” means the Securities Purchase Agreement,
dated as of October 5, 2007, by and among the Company, the Guarantor and the
Purchasers named therein, pursuant to which this Note was originally issued.

                “QIB” means a qualified institutional buyer as defined in Rule
144A.

                “Rule 144A” means Rule 144A as promulgated by the SEC under the
Securities Act or any successor thereto.

                “SEC” means the United States Securities and Exchange
Commission.

                “Securities Act” means the Securities Act of 1933, as amended.

                Section 2. Payments of Principal and Interest; Extension Option.

                (a) Interest. The Company shall pay interest accruing on this
Note (from the date hereof) on all outstanding Principal Amount of this Note at
the Interest Rate, in cash, on the earlier of (i) the Final Maturity Date, or
(ii) the date that the entire outstanding Principal Amount of this Note is
prepaid pursuant to Section 2(c).

                (b) Principal. The entire outstanding Principal Amount of this
Note, plus any and all default payments owing under the Transaction Documents
but not previously paid, shall become due and payable on the Final Maturity
Date.

                 (c) Prepayment. At any time following the Issuance Date, upon
delivery of a written notice to the Holder, the Company shall be entitled to
prepay in cash all or any portion of the outstanding Principal Amount of this
Note, plus any accrued and unpaid interest thereon.

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Notwithstanding the foregoing, the Company’s prepayment of this Note will not
terminate or otherwise extinguish the Warrants.

                (d) Extension Option. Upon the terms and subject to the
conditions of this Section 2(d), the Company shall have the right and option to
extend the Initial Maturity Date for up to sixty (60) additional days, upon
written notice delivered to the Holder no less than three (3) Business Days
prior to the Initial Maturity Date; provided, however, if this Note is not paid
in full in cash on the Initial Maturity Date, this extension will be deemed
exercised. In consideration for any such extension, (i) the Holder shall be
entitled to receive an additional Warrant to purchase 2% of the fully diluted
Common Stock and (ii) the Interest Rate shall increase to 25% per annum from the
date of such extension until all amounts owing under this Note and the other
Transaction Documents have been paid in full in cash. Any such Warrant shall be
in the form attached to the Purchase Agreement as Exhibit C, and shall be
executed by the Company and delivered to the Holder on or prior to the first day
of the extension period.

                Section 3. Cancellation and Notice.

                (a) Cancellation. After the entire Principal Amount (including
accrued but unpaid interest and default payments at any time owed on this Note)
has been paid in full in cash, this Note shall automatically be deemed canceled
and the Holder shall promptly surrender this Note to the Company at the
Company’s principal executive offices; provided, however, that the failure to
surrender this Note shall not delay or limit such cancellation.

                (b) Notice Procedures. Any and all notices or other
communications or deliveries to be provided by the Holder under this Note, shall
be in writing and delivered personally, by confirmed facsimile, or by a
nationally recognized overnight courier service to the Company at the facsimile
telephone number or address of the principal place of business of the Company as
set forth in, or provided pursuant to, the Purchase Agreement. Any and all
notices or other communications or deliveries to be provided by the Company
hereunder shall be in writing and delivered personally, by facsimile, or by a
nationally recognized overnight courier service addressed to the Holder at the
facsimile telephone number or address of the Holder appearing on the books of
the Company, or if no such facsimile telephone number or address appears, at the
principal place of business of the Holder. Any notice or other communication or
deliveries hereunder shall be deemed delivered (i) upon receipt, when delivered
personally, (ii) when sent by facsimile, upon receipt if received on a Business
Day prior to 5:00 p.m. (Pacific Time), or on the first Business Day following
such receipt if received on a Business Day after 5:00 p.m. (Pacific Time) or on
a day that is not a Business Day or (iii) upon receipt, when deposited with a
nationally recognized overnight courier service.

      Section 4. Defaults and Remedies.

                (a) Events of Default. An “Event of Default” is: (i) a failure
to pay any Principal Amount of this Note when due, whether at the Final Maturity
Date or otherwise, (ii) a failure to pay any interest due on this Note on the
date such payment is due, which failure continues for two Business Days (or ten
Business Days if such failure results from a Force Majeure Event or if the
Company can prove that funds were in fact wired from the Company’s account by
the due date); (iii) failure by the Company for 20 days (or 90 days if such
failure

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results from a Force Majeure Event) after written notice has been received by
the Company from the Holder to comply with any material provision (other than as
provided in the immediately preceding clauses (i) and (ii)) of this Note or any
other Transaction Document (including, without limitation, the failure to redeem
this Note upon the Holder’s request following a Change in Control Transaction);
(iv) a material breach by the Company of its representations or warranties in
this Note or in any other Transaction Document that continues for 10 days after
written notice to the Company; (v) any default after any cure period under, or
acceleration prior to maturity of, any note, mortgage, indenture or instrument
under which there may be issued or by which there may be secured or evidenced
any indebtedness for money borrowed by the Company for in excess of $50,000, or
for money borrowed the repayment of which is guaranteed by the Company for in
excess of $50,000, whether such indebtedness or guarantee now exists or shall be
created hereafter; (vi) the Company being subject to any Bankruptcy Event; (vii)
the creation of any security interest or lien purported to be created by the
Security Agreement ceasing to be in full force and effect with respect to a
material portion of the collateral thereunder or any such security interest or
lien being asserted by the Company or any Subsidiary of the Company or the
Guarantor not to be a valid, perfected, first priority (except as otherwise
permitted by the Transaction Documents) security interest in or lien on the
collateral covered thereby, and the failure of such security interest or lien to
be restored to full force and effect within 10 days after notice to the Company;
or (viii) any Transaction Document or any material provisions thereof at any
time and for any reason being declared by a court of competent jurisdiction to
be null and void, or the Company or any Subsidiary of the Company or the
Guarantor shall repudiate or deny any portion of its liabilities or obligations
thereunder.

                (b) Remedies. If an Event of Default occurs and is continuing,
the Holder may declare all of the then outstanding Principal Amount of this
Note, and any accrued and unpaid interest thereon, to be due and payable
immediately in cash, except that in the case of an Event of Default arising from
events described in clauses (v) and (vi) of Section 4(a), this Note shall become
automatically due and payable without further action or notice, and the Holder
may exercise all other rights and remedies set forth in the Transaction
Documents and any other rights and remedies available at law or in equity. The
date on which the Holder declares all of the then outstanding Principal Amount
of this Note, and any accrued and unpaid interest thereon, to be due and payable
immediately in cash, or the date on which this Note becomes automatically due
and payable without further action or notice as a result of an Event of Default
arising from any event described in clauses (v) and (vi) of Section 4(a), is
referred to herein as the “Acceleration Date”. In the event of such
acceleration, the amount due and owing to the Holder shall be 100% of the
outstanding Principal Amount of this Note (plus all accrued and unpaid interest,
if any). In any event the Company shall pay interest on such amount in cash at
the Default Rate to the Holder if such amount is not paid within one Business
Day after the Acceleration Date. The remedies under this Note shall be
cumulative.

                (c) Additional Warrants. If the Notes are not paid in full in
cash on or before the 180th day following the Issuance Date, the Holder shall be
entitled to receive an additional Warrant to purchase 4% of the fully diluted
Common Stock. Any such Warrant shall be in the form attached to the Purchase
Agreement as Exhibit C and shall be executed by the Company and delivered to the
Holder on or prior to the day immediately following the 180th day following the
Issuance Date.

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                Section 5. Certain Covenants; General.

                (a) Rule 144A Information Requirement. Within the period prior
to the expiration of the holding period applicable to sales hereof under Rule
144(k) under the Securities Act (or any successor provision), the Company
covenants and agrees that it shall, during any period in which it is not subject
to Section 13 or 15(d) under the Exchange Act, make available to the Holder and
any prospective purchaser of this Note from the Holder, the information required
pursuant to Rule 144A(d)(4) under the Securities Act upon the request of the
Holder and it will take such further action as the Holder may reasonably
request, all to the extent required from time to time to enable the Holder to
sell this Note without registration under the Securities Act within the
limitations of the exemption provided by Rule 144A, as Rule 144A may be amended
from time to time. Upon the request of the Holder, the Company will deliver to
the Holder a written statement as to whether it has complied with such
requirements.

                (b) Payment of Expenses. If there is an uncured Event of
Default, the Company agrees to pay all charges and expenses, including
reasonable attorneys’ fees and expenses, which may be incurred by the Holder in
seeking to enforce its remedies in accordance with this Note.

                (c) Savings Clause. In case any provision of this Note is held
by a court of competent jurisdiction to be excessive in scope or otherwise
invalid or unenforceable, such provision shall be adjusted rather than voided,
if possible, so that it is enforceable to the maximum extent possible, and the
validity and enforceability of the remaining provisions of this Note will not in
any way be affected or impaired thereby. In no event shall the amount of
interest paid hereunder exceed the maximum rate of interest on the unpaid
principal balance hereof allowable by applicable law. If any sum is collected in
excess of the applicable maximum rate, the excess collected shall be applied to
reduce the principal debt. If the interest actually collected hereunder is still
in excess of the applicable maximum rate, the interest rate shall be reduced so
as not to exceed the maximum allowable under law.

                (d) Amendment. Neither this Note nor any term hereof may be
amended, waived, discharged or terminated other than by a written instrument
signed by the Company and Holder.

                (e) Assignment, Etc. The Holder may assign or transfer this
Note, subject to compliance with applicable securities laws, without the consent
of the Company. The Holder shall promptly notify the Company in writing of any
such assignment or transfer. The Company may not assign its rights or
obligations under this Note. This Note shall be binding upon the Company and its
successors and shall inure to the benefit of the Holder and its successors and
permitted assigns.

                (f) No Waiver. No failure on the part of the Holder to exercise,
and no delay in exercising any right, remedy or power hereunder shall operate as
a waiver thereof, nor shall any single or partial exercise by the Holder of any
right, remedy or power hereunder preclude any other or future exercise of any
other right, remedy or power. Each and every right, remedy or power hereby
granted to the Holder or allowed it by law or other agreement shall be

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cumulative and not exclusive of any other, and may be exercised by the Holder
from time to time.

                (g) Governing Law; Jurisdiction.

                (i) Governing Law. THIS NOTE WILL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF COLORADO WITHOUT REGARD TO ANY
CONFLICTS OF LAWS PROVISIONS THEREOF THAT WOULD OTHERWISE REQUIRE THE
APPLICATION OF THE LAW OF ANY OTHER JURISDICTION.

                (ii) Jurisdiction. The Company (i) hereby irrevocably submits to
the exclusive jurisdiction of the United States District Court sitting in the
Northern District of Texas and the courts of the State of Texas located in
Dallas, Texas, for the purposes of any suit, action or proceeding arising out of
or relating to this Note or the transactions contemplated hereby, and (ii)
hereby waives, and agrees not to assert in any such suit, action or proceeding,
any claim that it is not personally subject to the jurisdiction of such court,
that the suit, action or proceeding is brought in an inconvenient forum or that
the venue of the suit, action or proceeding is improper. The Company consents to
process being served in any such suit, action or proceeding by mailing a copy
thereof to the Company at the address in effect for notices to it under the
Purchase Agreement and agrees that such service shall constitute good and
sufficient service of process and notice thereof. Nothing in this Section
5(g)(ii) shall affect or limit any right to serve process in any other manner
permitted by law. The Company hereby agrees that if the Holder is the prevailing
party in any suit, action or proceeding arising out of or relating to this Note,
the Holder shall be entitled to reimbursement for legal fees from the Company.

                (iii) NO JURY TRIAL. The Company knowingly and voluntarily
waives any and all rights it may have to a trial by jury with respect to any
litigation based on, or arising out of, under, or in connection with, this Note.

                (h) Replacement Notes. This Note may be exchanged by Holder at
any time and from time to time for a Note or Notes with different denominations
representing an equal aggregate outstanding Principal Amount, as reasonably
requested by Holder, upon surrendering the same. No service charge will be made
for such registration or exchange. In the event that Holder notifies the Company
that this Note has been lost, stolen or destroyed, a replacement Note identical
in all respects to the original Note (except for registration number and
Principal Amount, if different than that shown on the original Note), shall be
issued to the Holder, without requirement for any surety bond, provided that the
Holder executes and delivers to the Company an agreement reasonably satisfactory
to the Company to indemnify the Company from any loss incurred by it in
connection with this Note.

[Signature Page Follows]

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     IN WITNESS WHEREOF, the Company has caused this Note to be duly executed on
the day and in the year first above written.

TATONKA OIL AND GAS COMPANY,
INC.

By:                                                                 
Name:                                                                 
Title:                                                               

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ASSIGNMENT

     For value received ____________________ hereby sell(s), assign(s) and
transfer(s) unto ____________________ (Please insert social security or other
Taxpayer Identification Number of assignee:
____________________) the within Note, and hereby irrevocably constitutes and
appoints ____________________ attorney to transfer the said Note on the books of
Tatonka Oil and Gas Company, Inc., a Colorado corporation (the “Company”), with
full power of substitution in the premises.

     In connection with any transfer of the Note within the period prior to the
expiration of the holding period applicable to sales thereof under Rule 144(k)
under the Securities Act (or any successor provision) (other than any transfer
pursuant to a registration statement that has been declared effective under the
Securities Act), the undersigned confirms that such Note is being transferred:

 [    ]  To the Company or a subsidiary thereof; or       [     ] To a QIB
pursuant to and in compliance with Rule 144A; or       [    ]   To an
“accredited investor” pursuant to and in compliance with  the          
Securities Act; or       [     ] Pursuant to and in compliance with Rule 144
under the Securities Act;     

and unless the box below is checked, the undersigned confirms that, to the
knowledge of the undersigned, such Note is not being transferred to an
“affiliate” of the Company as defined in Rule 144 under the Securities Act (an
“Affiliate”).

   [   ]   The transferee is an Affiliate of the Company. 

     Capitalized terms used in this Assignment and not defined in this
Assignment shall have the respective meanings provided in the Note.

Dated:    NAME:    

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Signature(s) 

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